Some S is P._ Such knowledge, as that _All S_ (the whole of it) _is P_, is too precious a thing to be squandered in pure Logic; and it may be preserved by quantifying the predicate; for if we convert A.to Y., thus-- _All S is P .'.

Some P is all S--_ we may reconvert Y.to A.without any loss of meaning.

It is the chief use of quantifying the predicate that, thereby, every proposition is capable of simple conversion.
The conversion of propositions in which the relation of terms is inadequately expressed (see chap.ii., Sec.

2) by the ordinary copula (_is_ or _is not_) needs a special rule.

To argue thus-- _A is followed by B_ .'.