The matters which terms are used to denote are often so complicated or so refined in the assemblage, interfusion, or gradation of their qualities, that terms do not exist in sufficient abundance and discriminativeness to denote the things and, at the same time, to convey by connotation a determinate sense of their agreements and differences.

In discussing politics, religion, ethics, aesthetics, this imperfection of language is continually felt; and the only escape from it, short of coining new words, is to use such words as we have, now in one sense, now in another somewhat different, and to trust to the context, or to the resources of the literary art, in order to convey the true meaning.

Against this evil the having been born since Dryden is no protection.

It behoves us, then, to remember that terms are not classifiable into Univocal and AEquivocal, but that all terms are susceptible of being used aequivocally, and that honesty and lucidity require us to try, as well as we can, to use each term univocally in the same context.
The context of any proposition always proceeds upon some assumption or understanding as to the scope of the discussion, which controls the interpretation of every statement and of every word.

This was called by De Morgan the "universe of discourse": an older name for it, revived by Dr.Venn, and surely a better one, is _suppositio_.