a
thing consists in replacing it by another, if thinking the absence of
one thing is only possible by the more or less explicit representation
of the presence of some other thing, if, in short, annihilation
signifies before anything else substitution, the idea of an
"annihilation of everything" is as absurd as that of a square circle.
The absurdity is not obvious, because there exists no particular object
that cannot be supposed annihilated; then, from the fact that there is
nothing to prevent each thing in turn being suppressed in thought, we
conclude that it is possible to suppose them suppressed altogether. We
do not see that suppressing each thing in turn consists precisely in
replacing it in proportion and degree by another, and therefore that the
suppression of absolutely everything implies a downright contradiction
in terms, since the operation consists in destroying the very condition
that makes the operation possible.

But the illusion is tenacious. Though suppressing one thing consists _in
fact_ in substituting another for it, we do not conclude, we are
unwilling to conclude, that the annihilation of a thing _in thought_
implies the substitution in thought of a new thing for the old. We agree
that a thing is always replaced by another thing, and even that our mind
cannot think the disappearance of an object, external or internal,
without thinking--under an indeterminate and confused form, it is
true--that another object is substituted for it. But we add that the
representation of a disappearance is that of a phenomenon that is
produced in space or at least in time, that consequently it still
implies the calling up of an image, and that it is precisely here that
we have to free ourselves from the imagination in order to appeal to the
pure understanding. "Let us therefore no longer speak," it will be said,
"of disappearance or annihilation; these are physical operations. Let us
no longer represent the object A as annihilated or absent. Let us say
simply that we think it "non-existent." To annihilate it is to act on it
in time and perhaps also in space; it is to accept, consequently, the
condition of spatial and temporal existence, to accept the universal
connection that binds an object to all others, and prevents it from
disappearing without being at the same time replaced. But we can free
ourselves from these conditions; all that is necessary is that by an
effort of abstraction we should call up the idea of th