it moves, what we really do is to extricate a group of sensations on
which our thoughts are fastened and which is of relatively greater
stability than the others, from the stream of all our sensations.
Absolutely unalterable this group is not. Now this, now that member of
it appears and disappears, or is altered. In its full identity it never
recurs. Yet the sum of its constant elements as compared with the sum of
its changeable ones, especially if we consider the continuous character
of the transition, is always so great that for the purpose in hand the
former usually appear sufficient to determine the body's identity. But
because we can separate from the group every single member without the
body's ceasing to be for us the same, we are easily led to believe that
after abstracting all the members something additional would remain. It
thus comes to pass that we form the notion of a substance distinct from
its attributes, of a thing-in-itself, whilst our sensations are regarded
merely as symbols or indications of the properties of this
thing-in-itself. But it would be much better to say that bodies or
things are compendious mental symbols for groups of sensations--symbols
that do not exist outside of thought. Thus, the merchant regards the
labels of his boxes merely as indexes of their contents, and not the
contrary. He invests their contents, not their labels, with real value.
The same economy which induces us to analyse a group and to establish
special signs for its component parts, parts which also go to make up
other groups, may likewise induce us to mark out by some single symbol a
whole group.
On the old Egyptian monuments we see objects represented which do not
reproduce a single visual impression, but are composed of various
impressions. The heads and the legs of the figures appear in profile,
the head-dress and the breast are seen from the front, and so on. We
have here, so to speak, a mean view of the objects, in forming which the
sculptor has retained what he deemed essential, and neglected what he
thought indifferent. We have living exemplifications of the processes
put into stone on the walls of these old temples, in the drawings of our
children, and we also observe a faithful analogue of them in the
formation of ideas in our own minds. Only in virtue of some such
facility of view as that indicated, are we allowed to speak of a body.
When we speak of a cube with trimmed corners--a figure which is not a
cube--we do so from a natural instinct of economy, which prefers to add
to an old familiar conception a correction instead of forming an
entirely new one. This is the process of all judgment.
The crude notion of "body" can no more stand the test of analysis than
can the art of the Egyptians or that of our little children. The
physicist who sees a body flexed, stretched, melted, and vaporised, cuts
up this body into smaller permanent parts; the chemist splits it up into
elements. Yet even an element is not unalterable. Take sodium. When
warmed, the white, silvery mass becomes a liquid, which, when the heat
is increased and the air shut out, is transformed into a violet vapor,
and on the heat being still more increased glows with a yellow light. If
the name sodium is still retained, it is because of the continuous
character of the transitions and from a necessary instinct of economy.
By condensing the vapor, the white metal may be made to reappear.
Indeed, even after the metal is thrown into water and has passed into
sodium hydroxide, the vanished properties may by skilful treatment still
be made to appear; just as a moving body which has passed behind a
column and is lost to view for a moment may make its appearance after a
time. It is unquestionably very convenient always to have ready the name
and thought for a group of properties wherever that group by any
possibility can appear. But more than a compendious economical symbol
for these phenomena, that name and thought is not. It would be a mere
empty word for one in whom it did not awaken a large group of
well-ordered sense-impressions. And the same is true of the molecules
and atoms into which the chemical element is still further analysed.
True, it is customary to regard the conservation of weight, or, more
precisely, the conservation of mass, as a direct proof of the constancy
of matter. But this proof is dissolved, when we go to the bottom of it,
into such a multitude of instrumental and intellectual operations, that
in a sense it will be found to constitute simply an equation which our
ideas in imitating facts have to satisfy. That obscure, mysterious lump
which we involuntarily add in thought, we seek for in vain outside the
mind.
It is always, thus, the crude notion of substance that is slipping
unnoticed into science, proving itself constantly insufficient, and ever
under the necessity of being reduced to smaller and smaller
world-particles. Here, as elsewhere, the lower stage is not rendered
indispensable by the higher which is built upon it, no more than the
simplest mode of locomotion, walking, is rendered superfluous by the
most elaborate means of transportation. Body, as a compound of light and
touch sensations, knit together by sensations of space, must be as
familiar to the physicist who seeks it, as to the animal who hunts its
prey. But the student of the theory of knowledge, like the geologist and
the astronomer, must be permitted to reason back from the forms which
are created before his eyes to others which he finds ready made for
him.
All physical ideas and principles are succinct directions, frequently
involving subordinate directions, for the employment of economically
classified experiences, ready for use. Their conciseness, as also the
fact that their contents are rarely exhibited in full, often invests
them with the semblance of independent existence. Poetical myths
regarding such ideas,--for example, that of Time, the producer and
devourer of all things,--do not concern us here. We need only remind the
reader that even Newton speaks of an _absolute_ time independent of all
phenomena, and of an absolute space--views which even Kant did not shake
off, and which are often seriously entertained to-day. For the natural
inquirer, determinations of time are merely abbreviated statements of
the dependence of one event upon another, and nothing more. When we say
the acceleration of a freely falling body is 9·810 metres per second, we
mean the velocity of the body with respect to the centre of the earth is
9·810 metres greater when the earth has performed an additional 86400th
part of its rotation--a fact which itself can be determined only by the
earth's relation to other heavenly bodies. Again, in velocity is
contained simply a relation of the position of a body to the position of
the earth.[65] Instead of referring events to the earth we may refer
them to a clock, or even to our internal sensation of time. Now, because
all are connected, and each may be made the measure of the rest, the
illusion easily arises that time has significance independently of
all.[66]
The aim of research is the discovery of the equations which subsist
between the elements of phenomena. The equation of an ellipse expresses
the universal _conceivable_ relation between its co-ordinates, of which
only the real values have _geometrical_ significance. Similarly, the
equations between the elements of _phenomena_ express a universal,
mathematically conceivable relation. Here, however, for many values only
certain directions of change are _physically_ admissible. As in the
ellipse only certain _values_ satisfying the equation are realised, so
in the physical world only certain _changes_ of value occur. Bodies are
always accelerated towards the earth. Differences of temperature, left
to themselves, always grow less; and so on. Similarly, with respect to
space, mathematical and physiological researches have shown that the
space of experience is simply an _actual_ case of many conceivable
cases, about whose peculiar properties experience alone can instruct us.
The elucidation which this idea diffuses cannot be questioned, despite
the absurd uses to which it has been put.
Let us endeavor now to summarise the results of our survey. In the
economical schematism of science lie both its strength and its weakness.
Facts are always represented at a sacrifice of completeness and never
with greater precision than fits the needs of the moment. The
incongruence between thought and experience, therefore, will continue to
subsist as long as the two pursue their course side by side; but it will
be continually diminished.
In reality, the point involved is always the completion of some partial
experience; the derivation of one portion of a phenomenon from some
other. In this act our ideas must be based directly upon sensations. We
call this measuring.[67] The condition of science, both in its origin
and in its application, is a _great relative stability_ of our
environment. What it teaches us is interdependence. Absolute forecasts,
consequently, have no significance in science. With great changes in
celestial space we should lose our co-ordinate systems of space and
time.
When a geometer wishes to understand the form of a curve, he first
resolves it into small rectilinear elements. In doing this, however, he
is fully aware that these elements are only provisional and arbitrary
devices for comprehending in parts what he cannot comprehend as a whole.
When the law of the curve is found he no longer thinks of the elements.
Similarly, it would not become physical science to see in its
self-created, changeable, economical tools, molecules and atoms,
realities behind phenomena, forgetful of the lately acquired sapience of
her older sister, philosophy, in substituting a mechanical mythology for
the old animistic or metaphysical scheme, and thus creating no end of
suppositious problems. The atom must remain a tool for representing
phenomena, like the functions of mathematics. Gradually, however, as the
intellect, by contact with its subject-matter, grows in discipline,
physical science will give up its mosaic play with stones and will seek
out the boundaries and forms of the bed in which the living stream of
phenomena flows. The goal which it has set itself is the _simplest_ and
_most economical_ abstract expression of facts.
* * * * *
The question now remains, whether the same method of research which till
now we have tacitly restricted to physics, is also applicable in the
psychical domain. This question will appear superfluous to the physical
inquirer. Our physical and psychical views spring in exactly the same
manner from instinctive knowledge. We read the thoughts of men in their
acts and facial expressions without knowing how. Just as we predict the
behavior of a magnetic needle placed near a current by imagining
Ampère's swimmer in the current, similarly we predict in thought the
acts and behavior of men by assuming sensations, feelings, and wills
similar to our own connected with their bodies. What we here
instinctively perform would appear to us as one of the subtlest
achievements of science, far outstripping in significance and ingenuity
Ampère's rule of the swimmer, were it not that every child unconsciously
accomplished it. The question simply is, therefore, to grasp
scientifically, that is, by conceptional thought, what we are already
familiar with from other sources. And here much is to be accomplished. A
long sequence of facts is to be disclosed between the physics of
expression and movement and feeling and thought.
We hear the question, "But how is it possible to explain feeling by the
motions of the atoms of the brain?" Certainly this will never be done,
no more than light or heat will ever be deduced from the law of
refraction. We need not deplore, therefore, the lack of ingenious
solutions of this question. The problem is not a problem. A child
looking over the walls of a city or of a fort into the moat below sees
with astonishment living people in it, and not knowing of the portal
which connects the wall with the moat, cannot understand how they could
have got down from the high ramparts. So it is with the notions of
physics. We cannot climb up into the province of psychology by the
ladder of our abstractions, but we can climb down into it.
Let us look at the matter without bias. The world consists of colors,
sounds, temperatures, pressures, spaces, times, and so forth, which now
we shall not call sensations, nor phenomena, because in either term an
arbitrary, one-sided theory is embodied, but simply _elements_. The
fixing of the flux of these elements, whether mediately or immediately,
is the real object of physical research. As long as, neglecting our own
body, we employ ourselves with the interdependence of those groups of
elements which, including men and animals, make up _foreign_ bodies, we
are physicists. For example, we investigate the change of the red color
of a body as produced by a change of illumination. But the moment we
consider the special influence on the red of the elements constituting
our body, outlined by the well-known perspective with head invisible, we
are at work in the domain of physiological psychology. We close our
eyes, and the red together with the whole visible world disappears.
There exists, thus, in the perspective field of every sense a portion
which exercises on all the rest a different and more powerful influence
than the rest upon one another. With this, however, all is said. In the
light of this remark, we call _all_ elements, in so far as we regard
them as dependent on this special part (our body), _sensations_. That
the world is our sensation, in this sense, cannot be questioned. But to
make a system of conduct out of this provisional conception, and to
abide its slaves, is as unnecessary for us as would be a similar course
for a mathematician who, in varying a series of variables of a function
which were previously assumed to be constant, or in interchanging the
independent variables, finds his method to be the source of some very
surprising ideas for him.[68]
If we look at the matter in this unbiassed light it will appear
indubitable that the method of physiological psychology is none other
than that of physics; what is more, that this science is a part of
physics. Its subject-matter is not different from that of physics. It
will unquestionably determine the relations the sensations bear to the
physics of our body. We have already learned from a member of this
academy (Hering) that in all probability a sixfold manifoldness of the
chemical processes of the visual substance corresponds to the sixfold
manifoldness of color-sensation, and a threefold manifoldness of the
physiological processes to the threefold manifoldness of
space-sensations. The paths of reflex actions and of the will are
followed up and disclosed; it is ascertained what region of the brain
subserves the function of speech, what region the function of
locomotion, etc. That which still clings to our body, namely, our
thoughts, will, when those investigations are finished, present no
difficulties new in principle. When experience has once clearly
exhibited these facts and science has marshalled them in economic and
perspicuous order, there is no doubt that we shall _understand_ them.
For other "understanding" than a mental mastery of facts never existed.
Science does not create facts from facts, but simply _orders_ known
facts.
Let us look, now, a little more closely into the modes of research of
physiological psychology. We have a very clear idea of how a body moves
in the space encompassing it. With our optical field of sight we are
very familiar. But we are unable to state, as a rule, how we have come
by an idea, from what corner of our intellectual field of sight it has
entered, or by what region the impulse to a motion is sent forth.
Moreover, we shall never get acquainted with this mental field of view
from self-observation alone. Self-observation, in conjunction with
physiological research, which seeks out physical connexions, can put
this field of vision in a clear light before us, and will thus first
really reveal to us our inner man.
Primarily, natural science, or physics, in its widest sense, makes us
acquainted with only the firmest connexions of groups of elements.
Provisorily, we may not bestow too much attention on the single
constituents of those groups, if we are desirous of retaining a
comprehensible whole. Instead of equations between the primitive
variables, physics gives us, as much the easiest course, equations
between _functions_ of those variables. Physiological psychology teaches
us how to separate the visible, the tangible, and the audible from
bodies--a labor which is subsequently richly requited, as the division
of the subjects of physics well shows. Physiology further analyses the
visible into light and space sensations; the first into colors, the last
also into their component parts; it resolves noises into sounds, these
into tones, and so on. Unquestionably this analysis can be carried much
further than it has been. It will be possible in the end to exhibit the
common elements at the basis of very abstract but definite logical acts
of like form,--elements which the acute jurist and mathematician, as it
were, _feels_ out, with absolute certainty, where the uninitiated hears
only empty words. Physiology, in a word, will reveal to us the true real
elements of the world. Physiological psychology bears to physics in its
widest sense a relation similar to that which chemistry bears to physics
in its narrowest sense. But far greater than the mutual support of
physics and chemistry will be that which natural science and psychology
will render each other. And the results that shall spring from this
union will, in all likelihood, far outstrip those of the modern
mechanical physics.
What those ideas are with which we shall comprehend the world when the
closed circuit of physical and psychological facts shall lie complete
before us, (that circuit of which we now see only two disjoined parts,)
cannot be foreseen at the outset of the work. The men will be found who
will see what is right and will have the courage, instead of wandering
in the intricate paths of logical and historical accident, to enter on
the straight ways to the heights from which the mighty stream of facts
can be surveyed. Whether the notion which we now call matter will
continue to have a scientific significance beyond the crude purposes of
common life, we do not know. But we certainly shall wonder how colors
and tones which were such innermost parts of us could suddenly get lost
in our physical world of atoms; how we could be suddenly surprised that
something which outside us simply clicked and beat, in our heads should
make light and music; and how we could ask whether matter can feel, that
is to say, whether a mental symbol for a group of sensations can feel?
We cannot mark out in hard and fast lines the science of the future, but
we can foresee that the rigid walls which now divide man from the world
will gradually disappear; that human beings will not only confront each
other, but also the entire organic and so-called lifeless world, with
less selfishness and with livelier sympathy. Just such a presentiment as
this perhaps possessed the great Chinese philosopher Licius some two
thousand years ago when, pointing to a heap of mouldering human bones,
he said to his scholars in the rigid, lapidary style of his tongue:
"These and I alone have the knowledge that we neither live nor are
dead."
FOOTNOTES:
[Footnote 60: An address delivered before the anniversary meeting of
the Imperial Academy of Sciences, at Vienna, May 25, 1882.]
[Footnote 61: _Primitive Culture._]
[Footnote 62: Tylor, _loc. cit._]
[Footnote 63: _Essai philosophique sur les probabilités_. 6th Ed.
Paris, 1840, p. 4. The necessary consideration of the initial
velocities is lacking in this formulation.]
[Footnote 64: _Principien der Wirthschaftslehre_, Vienna, 1873.]
[Footnote 65: It is clear from this that all so-called elementary
(differential) laws involve a relation to the whole.]
[Footnote 66: If it be objected, that in the case of perturbations
of the velocity of rotation of the earth, we could be sensible of
such perturbations, and being obliged to have some measure of time,
we should resort to the period of vibration of the waves of sodium
light,--all that this would show is that for practical reasons we
should select that event which best served us as the _simplest_
common measure of the others.]
[Footnote 67: Measurement, in fact, is the definition of one
phenomenon by another (standard) phenomenon.]
[Footnote 68: I have represented the point of view here taken for
more than thirty years and developed it in various writings
(_Erhaltung der Arbeit_, 1872, parts of which are published in the
article on _The Conservation of Energy_ in this collection; _The
Forms of Liquids_, 1872, also published in this collection; and the
_Bewegungsempfindungen_, 1875). The idea, though known to
philosophers, is unfamiliar to the majority of physicists. It is a
matter of deep regret to me, therefore, that the title and author of
a small tract which accorded with my views in numerous details and
which I remember having caught a glance of in a very busy period
(1879-1880), have so completely disappeared from my memory that all
efforts to obtain a clue to them have hitherto been fruitless.]
ON TRANSFORMATION AND ADAPTATION IN SCIENTIFIC THOUGHT.[69]
It was towards the close of the sixteenth century that Galileo with a
superb indifference to the dialectic arts and sophistic subtleties of
the Schoolmen of his time, turned the attention of his brilliant mind to
nature. By nature his ideas were transformed and released from the
fetters of inherited prejudice. At once the mighty revolution was felt,
that was therewith effected in the realm of human thought--felt indeed
in circles far remote and wholly unrelated to the sphere of science,
felt in strata of society that hitherto had only indirectly recognised
the influence of scientific thought.
And how great and how far-reaching that revolution was! From the
beginning of the seventeenth century till its close we see arising, at
least in embryo, almost all that plays a part in the natural and
technical science of to-day, almost all that in the two centuries
following so wonderfully transformed the facial appearance of the earth,
and all that is moving onward in process of such mighty evolution
to-day. And all this, the direct result of Galilean ideas, the direct
outcome of that freshly awakened sense for the investigation of natural
phenomena which taught the Tuscan philosopher to form the concept and
the law of falling bodies from the _observation_ of a falling stone!
Galileo began his investigations without an implement worthy of the
name; he measured time in the most primitive way, by the efflux of
water. Yet soon afterwards the telescope, the microscope, the barometer,
the thermometer, the air-pump, the steam engine, the pendulum, and the
electrical machine were invented in rapid succession. The fundamental
theorems of dynamical science, of optics, of heat, and of electricity
were all disclosed in the century that followed Galileo.