20. Let it be granted, then, that reaction is not the contrary of
action. Nevertheless, as it differs therefrom, it could not share
the same genus. If both reaction and action be movements, they share
the same genus, that of alteration, which is a movement, as respects
quality.[279] When alteration proceeds from the being endowed with
quality, is there any action, though this being remain impassible? Yes,
for though impassible, it is active. It may be asked, is this being no
longer active when it acts on some other object, as, for instance, by
striking it, and then reacts? The answer is, that it would be active
and passive simultaneously. If it be active, when it reacts--when, for
instance, it rubs--why is it considered active rather than passive?
Because it reacts in being rubbed while it rubs. Could we say that,
because it is moved while moving, there were in it two movements? But
how could there be two movements in it? Shall we assert that there
is but one? In this case, how could the same movement be action and
reaction simultaneously? Doubtless, it will be considered action, in
so far as it proceeds from the mover; and reaction, inasmuch as it
passes from the mover into the moved; and this, without ceasing to be
one and the same thing. Would you say that reaction was a movement of
a kind different from action? How then would the altering movement
in a certain manner modify what reacts without an equal reaction in
what is acting? But how (can we conceive) of reaction in that which
acts on another object? Is the mere presence of the movement in the
moved sufficient to constitute reaction?[280] But if, on one hand, the
("seminal) reason" of the swan whitens, and on the other hand the swan
that is being born becomes white, shall we say that the swan is passive
in becoming what it is his nature to be? If he becomes white even after
his birth, is he still passive? If one thing increase, and another
thing be increased, will we admit that the thing that increases reacts?
Will we rather attribute reaction to the thing qualified? If one thing
be embellished, and another thing embellishes it, could we say that
the embellished thing reacts?[281] If however, the embellishing thing
decreases, and, like tin, tarnishes, or on the contrary, like copper,
takes on polish; shall we say that the tin acts, and the copper reacts
(that is, "suffers")? Besides, it would be impossible to say that that
which learns is passive (suffering)? Would this be because the action
of him who acts passes into him? But how could there be any reaction
("suffering") since there is nothing there but an act? This action,
no doubt, is not a reaction ("suffering"); but he who receives it is
passive, because he participates in passivity. Indeed, from the fact
that the learner does not himself act, it does not necessarily result
that he is passive; for learning is not being struck, but grasping and
discerning, as takes place with the process of vision.