This is the objection; and in order to the answering of it, I shall
premise these two things:

1. That the body of man is not a constant and permanent thing, always
continuing in the same state, and consisting of the same matter; but
a successive thing, which is continually spending and continually
renewing itself, every day losing something of the matter which it had
before, and gaining new; so that most men have new bodies oftener than
they have new clothes; only with this difference, that we change our
clothes commonly at once, but our bodies by degrees.

And this is undeniably certain from experience. For so much as our
bodies grow, so much new matter is added to them, over and beside the
repairing of what is continually spent; and after a man come to his
full growth, so much of his food as every day turns into nourishment,
so much of his yesterday's body is usually wasted, and carried off by
insensible perspiration--that is, breathed out at the pores of his
body; which, according to the static experiment of Sanctorius, a
learned physician, who, for several years together, weighed himself
exactly every day, is (as I remember) according to the proportion of
five to eight of all that a man eats and drinks. Now, according to
this proportion, every man must change his body several times in a
year.

It is true indeed the more solid parts of the body, as the bones, do
not change so often as the fluid and fleshy; but that they also do
change is certain, because they grow, and whatever grows is nourished
and spends, because otherwise it would not need to be repaired.