The words χρ⋯ and δεῖ with their inflectional and dialectic variations, are less definite and stable in their semantic range than the other Greek expressions for the general ideas of necessity, obligation, or propriety. Their semantic boundaries varied with the dialect, province of literature, and period–which cannot, indeed, be entirely separated. From Homer to Aristotle there is a steady trend, so plain that the slight notice taken of it is rather surprising. Everyone sees that the two are sometimes differentiated; yet it seems to be loosely taken for granted that they are substantially equivalent, and that either may, almost anywhere, be taken as an equivalent of the verbal in -τ⋯ος. The statements in Liddell and Scott under χρ⋯ present an admirable confusion of all periods and styles, and J. H. H. Schmidt, with no mention of dates, makes a distinction that resembles a reversal of the true relation.