12. Personality in change of substance.
But the question is, Whether if the same substance which thinks be
changed, it can be the same person; or, remaining the same, it can be different persons?
And to this I answer: First, This can be no question at all to those who place thought in a purely material animal
constitution, void of an immaterial substance. For, whether their supposition be true or no, it is plain they
conceive personal identity preserved in something else than identity of substance; as animal identity is preserved
in identity of life, and not of substance. And therefore those who place thinking in an immaterial substance only,
before they can come to deal with these men, must show why personal identity cannot be preserved in the change
of immaterial substances, or variety of particular immaterial substances, as well as animal identity is preserved in
the change of material substances, or variety of particular bodies: unless they will say, it is one immaterial spirit
that makes the same life in brutes, as it is one immaterial spirit that makes the same person in men; which the
Cartesians at least will not admit, for fear of making brutes thinking things too.
