Extension. Stretching out.
The quality of matter, in virtue of which every portion or particle of
it must occupy a certain portion of space.
The Cartesian school considers it the essence
of matter, which they distinguished from mind by calling the one res extensa and the other res cogitans. "Whatever is
extended is of necessity divisible, but when we think of the ultimate
atom, we exclude both the one and the other of these attributes. Whether
such ultimate atoms exist is a question, but there can be none that if
they do they are as their name imports, indivisible, and as such without
In logic the extension of a term means the number of objects, as its
comprehension the number of qualities, which it includes. See