world from which we start, its aspect as knowable, and therefore, in the
meantime, we must, without reserve, regard all presented objects, even our
own bodies (as we shall presently show more fully), merely as ideas, and
call them merely ideas. By so doing we always abstract from will (as we
hope to make clear to every one further on), which by itself constitutes
the other aspect of the world. For as the world is in one aspect entirely
_idea_, so in another it is entirely _will_. A reality which is neither of
these two, but an object in itself (into which the thing in itself has
unfortunately dwindled in the hands of Kant), is the phantom of a dream,
and its acceptance is an _ignis fatuus_ in philosophy.
§ 2. That which knows all things and is known by none is the subject. Thus
it is the supporter of the world, that condition of all phenomena, of all
objects which is always pre-supposed throughout experience; for all that
exists, exists only for the subject. Every one finds himself to be
subject, yet only in so far as he knows, not in so far as he is an object
of knowledge. But his body is object, and therefore from this point of
view we call it idea. For the body is an object among objects, and is
conditioned by the laws of objects, although it is an immediate object.
Like all objects of perception, it lies within the universal forms of
knowledge, time and space, which are the conditions of multiplicity. The
subject, on the contrary, which is always the knower, never the known,
does not come under these forms, but is presupposed by them; it has
therefore neither multiplicity nor its opposite unity. We never know it,
but it is always the knower wherever there is knowledge.
So then the world as idea, the only aspect in which we consider it at
present, has two fundamental, necessary, and inseparable halves. The one
half is the object, the forms of which are space and time, and through
these multiplicity. The other half is the subject, which is not in space
and time, for it is present, entire and undivided, in every percipient
being. So that any one percipient being, with the object, constitutes the
whole world as idea just as fully as the existing millions could do; but
if this one were to disappear, then the whole world as idea would cease to
be. These halves are therefore inseparable even for thought, for each of
the two has meaning and existence only through and for the other, each
appears with the other and vanishes with it. They limit each other
immediately; where the object begins the subject ends. The universality of
this limitation is shown by the fact that the essential and hence
universal forms of all objects, space, time, and causality, may, without
knowledge of the object, be discovered and fully known from a
consideration of the subject, _i.e._, in Kantian language, they lie _a
priori_ in our consciousness. That he discovered this is one of Kant’s
principal merits, and it is a great one. I however go beyond this, and
maintain that the principle of sufficient reason is the general expression
for all these forms of the object of which we are _a priori_ conscious;
and that therefore all that we know purely _a priori_, is merely the
content of that principle and what follows from it; in it all our certain
_a priori_ knowledge is expressed. In my essay on the principle of
sufficient reason I have shown in detail how every possible object comes
under it; that is, stands in a necessary relation to other objects, on the
one side as determined, on the other side as determining: this is of such
wide application, that the whole existence of all objects, so far as they
are objects, ideas and nothing more, may be entirely traced to this their
necessary relation to each other, rests only in it, is in fact merely
relative; but of this more presently. I have further shown, that the
necessary relation which the principle of sufficient reason expresses
generally, appears in other forms corresponding to the classes into which
objects are divided, according to their possibility; and again that by
these forms the proper division of the classes is tested. I take it for
granted that what I said in this earlier essay is known and present to the
reader, for if it had not been already said it would necessarily find its
place here.
§ 3. The chief distinction among our ideas is that between ideas of
perception and abstract ideas. The latter form just one class of ideas,
namely concepts, and these are the possession of man alone of all
creatures upon earth. The capacity for these, which distinguishes him from
all the lower animals, has always been called reason.(5) We shall consider
these abstract ideas by themselves later, but, in the first place, we
shall speak exclusively of the _ideas of perception_. These comprehend the
whole visible world, or the sum total of experience, with the conditions
of its possibility. We have already observed that it is a highly important
discovery of Kant’s, that these very conditions, these forms of the
visible world, _i.e._, the absolutely universal element in its perception,
the common property of all its phenomena, space and time, even when taken
by themselves and apart from their content, can, not only be thought in
the abstract, but also be directly perceived; and that this perception or
intuition is not some kind of phantasm arising from constant recurrence in
experience, but is so entirely independent of experience that we must
rather regard the latter as dependent on it, inasmuch as the qualities of
space and time, as they are known in _a priori_ perception or intuition,
are valid for all possible experience, as rules to which it must
invariably conform. Accordingly, in my essay on the principle of
sufficient reason, I have treated space and time, because they are
perceived as pure and empty of content, as a special and independent class
of ideas. This quality of the universal forms of intuition, which was
discovered by Kant, that they may be perceived in themselves and apart
from experience, and that they may be known as exhibiting those laws on
which is founded the infallible science of mathematics, is certainly very
important. Not less worthy of remark, however, is this other quality of
time and space, that the principle of sufficient reason, which conditions
experience as the law of causation and of motive, and thought as the law
of the basis of judgment, appears here in quite a special form, to which I
have given the name of the ground of being. In time, this is the
succession of its moments, and in space the position of its parts, which
reciprocally determine each other _ad infinitum_.
Any one who has fully understood from the introductory essay the complete
identity of the content of the principle of sufficient reason in all its
different forms, must also be convinced of the importance of the knowledge
of the simplest of these forms, as affording him insight into his own
inmost nature. This simplest form of the principle we have found to be
time. In it each instant is, only in so far as it has effaced the
preceding one, its generator, to be itself in turn as quickly effaced. The
past and the future (considered apart from the consequences of their
content) are empty as a dream, and the present is only the indivisible and
unenduring boundary between them. And in all the other forms of the
principle of sufficient reason, we shall find the same emptiness, and
shall see that not time only but also space, and the whole content of both
of them, _i.e._, all that proceeds from causes and motives, has a merely
relative existence, is only through and for another like to itself,
_i.e._, not more enduring. The substance of this doctrine is old: it
appears in Heraclitus when he laments the eternal flux of things; in Plato
when he degrades the object to that which is ever becoming, but never
being; in Spinoza as the doctrine of the mere accidents of the one
substance which is and endures. Kant opposes what is thus known as the
mere phenomenon to the thing in itself. Lastly, the ancient wisdom of the
Indian philosophers declares, “It is Mâyâ, the veil of deception, which
blinds the eyes of mortals, and makes them behold a world of which they
cannot say either that it is or that it is not: for it is like a dream; it
is like the sunshine on the sand which the traveller takes from afar for
water, or the stray piece of rope he mistakes for a snake.” (These similes
are repeated in innumerable passages of the Vedas and the Puranas.) But
what all these mean, and that of which they all speak, is nothing more
than what we have just considered—the world as idea subject to the
principle of sufficient reason.
§ 4. Whoever has recognised the form of the principle of sufficient
reason, which appears in pure time as such, and on which all counting and
arithmetical calculation rests, has completely mastered the nature of
time. Time is nothing more than that form of the principle of sufficient
reason, and has no further significance. Succession is the form of the
principle of sufficient reason in time, and succession is the whole nature
of time. Further, whoever has recognised the principle of sufficient
reason as it appears in the presentation of pure space, has exhausted the
whole nature of space, which is absolutely nothing more than that
possibility of the reciprocal determination of its parts by each other,
which is called position. The detailed treatment of this, and the
formulation in abstract conceptions of the results which flow from it, so
that they may be more conveniently used, is the subject of the science of
geometry. Thus also, whoever has recognised the law of causation, the
aspect of the principle of sufficient reason which appears in what fills
these forms (space and time) as objects of perception, that is to say
matter, has completely mastered the nature of matter as such, for matter
is nothing more than causation, as any one will see at once if he
reflects. Its true being is its action, nor can we possibly conceive it as
having any other meaning. Only as active does it fill space and time; its
action upon the immediate object (which is itself matter) determines that
perception in which alone it exists. The consequence of the action of any
material object upon any other, is known only in so far as the latter acts
upon the immediate object in a different way from that in which it acted
before; it consists only of this. Cause and effect thus constitute the
whole nature of matter; its true being is its action. (A fuller treatment
of this will be found in the essay on the Principle of Sufficient Reason,
§ 21, p. 77.) The nature of all material things is therefore very
appropriately called in German _Wirklichkeit_,(6) a word which is far more
expressive than _Realität_. Again, that which is acted upon is always
matter, and thus the whole being and essence of matter consists in the
orderly change, which one part of it brings about in another part. The
existence of matter is therefore entirely relative, according to a
relation which is valid only within its limits, as in the case of time and
space.
But time and space, each for itself, can be mentally presented apart from
matter, whereas matter cannot be so presented apart from time and space.
The form which is inseparable from it presupposes space, and the action in
which its very existence consists, always imports some change, in other
words a determination in time. But space and time are not only, each for
itself, presupposed by matter, but a union of the two constitutes its
essence, for this, as we have seen, consists in action, _i.e._, in
causation. All the innumerable conceivable phenomena and conditions of
things, might be coexistent in boundless space, without limiting each
other, or might be successive in endless time without interfering with
each other: thus a necessary relation of these phenomena to each other,
and a law which should regulate them according to such a relation, is by
no means needful, would not, indeed, be applicable: it therefore follows
that in the case of all co-existence in space and change in time, so long
as each of these forms preserves for itself its condition and its course
without any connection with the other, there can be no causation, and
since causation constitutes the essential nature of matter, there can be
no matter. But the law of causation receives its meaning and necessity
only from this, that the essence of change does not consist simply in the
mere variation of things, but rather in the fact that at the _same part of
space_ there is now _one thing_ and then _another_, and at _one_ and the
same point of time there is _here_ one thing and there _another_: only
this reciprocal limitation of space and time by each other gives meaning,
and at the same time necessity, to a law, according to which change must
take place. What is determined by the law of causality is therefore not
merely a succession of things in time, but this succession with reference
to a definite space, and not merely existence of things in a particular
place, but in this place at a different point of time. Change, _i.e._,
variation which takes place according to the law of causality, implies
always a determined part of space and a determined part of time together
and in union. Thus causality unites space with time. But we found that the
whole essence of matter consisted in action, _i.e._, in causation,
consequently space and time must also be united in matter, that is to say,
matter must take to itself at once the distinguishing qualities both of
space and time, however much these may be opposed to each other, and must
unite in itself what is impossible for each of these independently, that
is, the fleeting course of time, with the rigid unchangeable perduration
of space: infinite divisibility it receives from both. It is for this
reason that we find that co-existence, which could neither be in time
alone, for time has no contiguity, nor in space alone, for space has no
before, after, or now, is first established through matter. But the
co-existence of many things constitutes, in fact, the essence of reality,
for through it permanence first becomes possible; for permanence is only
knowable in the change of something which is present along with what is
permanent, while on the other hand it is only because something permanent
is present along with what changes, that the latter gains the special
character of change, _i.e._, the mutation of quality and form in the
permanence of substance, that is to say, in matter.(7) If the world were
in space alone, it would be rigid and immovable, without succession,
without change, without action; but we know that with action, the idea of
matter first appears. Again, if the world were in time alone, all would be
fleeting, without persistence, without contiguity, hence without
co-existence, and consequently without permanence; so that in this case
also there would be no matter. Only through the union of space and time do
we reach matter, and matter is the possibility of co-existence, and,
through that, of permanence; through permanence again matter is the
possibility of the persistence of substance in the change of its
states.(8) As matter consists in the union of space and time, it bears
throughout the stamp of both. It manifests its origin in space, partly
through the form which is inseparable from it, but especially through its
persistence (substance), the _a priori_ certainty of which is therefore
wholly deducible from that of space(9) (for variation belongs to time
alone, but in it alone and for itself nothing is persistent). Matter shows
that it springs from time by quality (accidents), without which it never
exists, and which is plainly always causality, action upon other matter,
and therefore change (a time concept). The law of this action, however,
always depends upon space and time together, and only thus obtains
meaning. The regulative function of causality is confined entirely to the
determination of what must occupy _this time and this space_. The fact
that we know _a priori_ the unalterable characteristics of matter, depends
upon this derivation of its essential nature from the forms of our
knowledge of which we are conscious _a priori_. These unalterable
characteristics are space-occupation, _i.e._, impenetrability, _i.e._,
causal action, consequently, extension, infinite divisibility,
persistence, _i.e._, indestructibility, and lastly mobility: weight, on
the other hand, notwithstanding its universality, must be attributed to _a
posteriori_ knowledge, although Kant, in his “Metaphysical Introduction to
Natural Philosophy,” p. 71 (p. 372 of Rosenkranz’s edition), treats it as
knowable _a priori_.
But as the object in general is only for the subject, as its idea, so
every special class of ideas is only for an equally special quality in the
subject, which is called a faculty of perception. This subjective
correlative of time and space in themselves as empty forms, has been named
by Kant pure sensibility; and we may retain this expression, as Kant was
the first to treat of the subject, though it is not exact, for sensibility
presupposes matter. The subjective correlative of matter or of causation,
for these two are the same, is understanding, which is nothing more than
this. To know causality is its one function, its only power; and it is a
great one, embracing much, of manifold application, yet of unmistakable
identity in all its manifestations. Conversely all causation, that is to
say, all matter, or the whole of reality, is only for the understanding,
through the understanding, and in the understanding. The first, simplest,
and ever-present example of understanding is the perception of the actual
world. This is throughout knowledge of the cause from the effect, and
therefore all perception is intellectual. The understanding could never
arrive at this perception, however, if some effect did not become known
immediately, and thus serve as a starting-point. But this is the affection
of the animal body. So far, then, the animal body is the _immediate
object_ of the subject; the perception of all other objects becomes
possible through it. The changes which every animal body experiences, are
immediately known, that is, felt; and as these effects are at once
referred to their causes, the perception of the latter as _objects_
arises. This relation is no conclusion in abstract conceptions; it does
not arise from reflection, nor is it arbitrary, but immediate, necessary,
and certain. It is the method of knowing of the pure understanding,
without which there could be no perception; there would only remain a dull
plant-like consciousness of the changes of the immediate object, which
would succeed each other in an utterly unmeaning way, except in so far as
they might have a meaning for the will either as pain or pleasure. But as
with the rising of the sun the visible world appears, so at one stroke,
the understanding, by means of its one simple function, changes the dull,
meaningless sensation into perception. What the eye, the ear, or the hand
feels, is not perception; it is merely its data. By the understanding
passing from the effect to the cause, the world first appears as
perception extended in space, varying in respect of form, persistent
through all time in respect of matter; for the understanding unites space
and time in the idea of matter, that is, causal action. As the world as
idea exists only through the understanding, so also it exists only for the
understanding. In the first chapter of my essay on “Light and Colour,” I
have already explained how the understanding constructs perceptions out of
the data supplied by the senses; how by comparison of the impressions
which the various senses receive from the object, a child arrives at
perceptions; how this alone affords the solution of so many phenomena of
the senses; the single vision of two eyes, the double vision in the case
of a squint, or when we try to look at once at objects which lie at
unequal distances behind each other; and all illusion which is produced by
a sudden alteration in the organs of sense. But I have treated this
important subject much more fully and thoroughly in the second edition of
the essay on “The Principle of Sufficient Reason,” § 21. All that is said
there would find its proper place here, and would therefore have to be
said again; but as I have almost as much disinclination to quote myself as
to quote others, and as I am unable to explain the subject better than it
is explained there, I refer the reader to it, instead of quoting it, and
take for granted that it is known.
The process by which children, and persons born blind who have been
operated upon, learn to see, the single vision of the double sensation of
two eyes, the double vision and double touch which occur when the organs
of sense have been displaced from their usual position, the upright
appearance of objects while the picture on the retina is upside down, the
attributing of colour to the outward objects, whereas it is merely an
inner function, a division through polarisation, of the activity of the
eye, and lastly the stereoscope,—all these are sure and incontrovertible
evidence that perception is not merely of the senses, but
intellectual—that is, _pure knowledge through the understanding of the
cause from the effect_, and that, consequently, it presupposes the law of
causality, in a knowledge of which all perception—that is to say all
experience, by virtue of its primary and only possibility, depends. The
contrary doctrine that the law of causality results from experience, which
was the scepticism of Hume, is first refuted by this. For the independence
of the knowledge of causality of all experience,—that is, its _a priori_
character—can only be deduced from the dependence of all experience upon
it; and this deduction can only be accomplished by proving, in the manner
here indicated, and explained in the passages referred to above, that the
knowledge of causality is included in perception in general, to which all
experience belongs, and therefore in respect of experience is completely
_a priori_, does not presuppose it, but is presupposed by it as a
condition. This, however, cannot be deduced in the manner attempted by
Kant, which I have criticised in the essay on “The Principle of Sufficient
Reason,” § 23.