materials; two real apples may have the same shape, but contain distinct
ounces of apple-stuff, so that after one is eaten the other remains to
be eaten. Similarly, tables may have the same shape, though one be made
of marble, another of oak, another of iron. The form is common to
several things, the matter is peculiar to each. Metaphysicians have
carried the distinction further: apples, they say, may have not only the
same outward shape, but the same inward constitution, which, therefore,
may be called the Form of apple-stuff itself--namely, a certain
pulpiness, juiciness, sweetness, etc.; qualities common to all dessert
apples: yet their Matter is different, one being here, another
there--differing in place or time, if in nothing else. The definition of
a species is the form of every specimen of it.

To apply this distinction to the things of Logic: it is easy to see how
two propositions may have the same Form but different Matter: not using
'Form' in the sense of 'shape,' but for that which is common to many
things, in contrast with that which is peculiar to each. Thus, _All male
lions are tawny_ and _All water is liquid at 50° Fahrenheit_, are two
propositions that have the same form, though their matter is entirely
different. They both predicate something of the whole of their subjects,
though their subjects are different, and so are the things predicated of
them. Again, _All male lions have tufted tails_ and _All male lions have
manes_, are two propositions having the same form and, in their
subjects, the same matter, but different matter in their predicates. If,
however, we take two such propositions as these: _All male lions have
manes_ and _Some male lions have manes_, here the matter is the same in
both, but the form is different--in the first, predication is made
concerning _every_ male lion; in the second of only _some_ male lions;
the first is _universal_, the second is _particular_. Or, again, if we
take _Some tigers are man-eaters_ and _Some tigers are not man-eaters_,