_Subcontrary_, are particular propositions of different quality; as, _some man is learned_, _some man is not learned_; which cannot be both false, but they may be both true. _Contradictory_ are those that differ both in quantity and quality; as, _every man is a living creature_, _some man is not a living-creature_; which can neither be both true, nor both false. [Sidenote: Consequence, what it is.] 18. A proposition is said to _follow_ from two other propositions, when these being granted to be true, it cannot be denied but the other is true also. For example, let these two propositions, _every man is a living creature_, and, _every living creature is a body_, be supposed true, that is, that _body_ is the name of _every living creature_, and _living creature_ the name of _every man_. Seeing therefore, if these be understood to be true, it cannot be understood that _body_ is not the name of _every man_, that is, that _every man is a body_ is false, this proposition will be said to _follow_ from those two, or to be necessarily _inferred_ from them. [Sidenote: Falsity cannot follow from truth.] 19. That a true proposition may follow from false propositions, may happen sometimes; but false from true, never. For if these, _every man is a stone_, and _every stone is a living creature_, (which are both false) be granted to be true, it is granted also that _living creature_ is the name of _every stone_, and _stone_ of _every man_, that is, that _living creature_ is the name of _every man_; that is to say, this proposition _every man is a living creature_, is true, as it is indeed true. Wherefore a true proposition may sometimes follow from false. But if any two propositions be true, a false one can never follow from them. For if true follow from false, for this reason only, that the false are granted to be true, then truth from two truths granted will follow in the same manner. [Sidenote: How one proposition is the cause of another.]