Then the reasoned inference of P from S cannot be made without M's intermediation. The 'essence' M is thus that third or middle term in the reasoning which a moment ago was pronounced essential. _For his original concrete S the reasoner substitutes its abstract property M._ What is true of M, what is coupled with M, thereupon holds true of S, is coupled with S. As M is properly one of the _parts_ of the entire S, _reasoning may then be very well defined as the substitution of parts and their implications or consequences for wholes_. And the art of the reasoner will consist of two stages: First, _sagacity_, or the ability to discover what part, M, lies embedded in the whole S which is before him; Second, _learning_, or the ability to recall promptly M's consequences, concomitants, or implications. If we glance at the ordinary syllogism-- M is P; S is M; ⁂ S is P --we see that the second or minor premise, the 'subsumption' as it is sometimes called, is the one requiring the sagacity; the first or major the one requiring the fertility, or fulness of learning. Usually the learning is more apt to be ready than the sagacity, the ability to seize fresh aspects in concrete things being rarer than the ability to learn old rules; so that, in most actual cases of reasoning, the minor premise, or the way of conceiving the subject, is the one that makes the novel step in thought. This is, to be sure, not always the case; for the fact that M carries P with it may also be unfamiliar and now formulated for the first time. The perception that S is M is a _mode of conceiving S_. The statement that M is P is an _abstract or general proposition_. A word about both is necessary.