§ 5. This leads to a very important distinction to which we shall often have to refer in subsequent pages--namely, the distinction between the Form and the Matter of a proposition or of an argument. The distinction between Form and Matter, as it is ordinarily employed, is easily understood. An apple growing in the orchard and a waxen apple on the table may have the same shape or form, but they consist of different 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_, here too the matter is the same, but the form is different; for the first proposition is _affirmative_, whilst the second is _negative_.