form an ape or any other irrational animal, we could have no means of
knowing that they were in any respect of a different nature from these
animals; but if there were machines bearing the image of our bodies, and
capable of imitating our actions as far as it is morally possible, there
would still remain two most certain tests whereby to know that they were
not therefore really men. Of these the first is that they could never use
words or other signs arranged in such a manner as is competent to us in
order to declare our thoughts to others: for we may easily conceive a
machine to be so constructed that it emits vocables, and even that it
emits some correspondent to the action upon it of external objects which
cause a change in its organs; for example, if touched in a particular
place it may demand what we wish to say to it; if in another it may cry
out that it is hurt, and such like; but not that it should arrange them
variously so as appositely to reply to what is said in its presence, as
men of the lowest grade of intellect can do. The second test is, that
although such machines might execute many things with equal or perhaps
greater perfection than any of us, they would, without doubt, fail in
certain others from which it could be discovered that they did not act
from knowledge, but solely from the disposition of their organs: for while
reason is an universal instrument that is alike available on every
occasion, these organs, on the contrary, need a particular arrangement for
each particular action; whence it must be morally impossible that there
should exist in any machine a diversity of organs sufficient to enable it
to act in all the occurrences of life, in the way in which our reason
enables us to act. Again, by means of these two tests we may likewise know
the difference between men and brutes. For it is highly deserving of
remark, that there are no men so dull and stupid, not even idiots, as to
be incapable of joining together different words, and thereby constructing
a declaration by which to make their thoughts understood; and that on the
other hand, there is no other animal, however perfect or happily