It has been proposed, indeed, with a view to superficial simplification, to turn all Negatives into Infinites, and thus render all propositions Affirmative in Quality.

But although every proposition both affirms and denies something according to the aspect in which you regard it (as _Snow is white_ denies that it is any other colour, and _Snow is not blue_ affirms that it is some other colour), yet there is a great difference between the definite affirmation of a genuine affirmative and the vague affirmation of a negative or infinite; so that materially an affirmative infinite is the same as a negative.
Generally Mill's remark is true, that affirmation and denial stand for distinctions of fact that cannot be got rid of by manipulation of words.
Whether granite sinks in water, or not; whether the rook lives a hundred years, or not; whether a man has a hundred dollars in his pocket, or not; whether human bones have ever been found in Pliocene strata, or not; such alternatives require distinct forms of expression.

At the same time, it may be granted that many facts admit of being stated with nearly equal propriety in either Quality, as _No man is proof against flattery_, or _All men are open to flattery_.
But whatever advantage there is in occasionally changing the Quality of a proposition may be gained by the process of Obversion (chap.vii.

Sec.
5); whilst to use only one Quality would impair the elasticity of logical expression.

It is a postulate of Logic that the negative sign may be transferred from the copula to the predicate, or from the predicate to the copula, without altering the sense of a proposition; and this is justified by the experience that not to have an attribute and to be without it are the same thing.
Sec.3.