“…there is a particular boldness in metaphor, which is not to be found in the same degree in any of the figures of rhetoric. Without any thing like an explicit comparison, and commonly without any warning or apology, the name of one thing is obtruded upon us, for the name of another quite different, though resembling in some quality. The consequence of this is, that as there is always in this trope an apparent at least, if it cannot be called a real impropriety, and some degree of obscurity, a new metaphor is rarely to be risked.” MetaphorTropesImpropriety Book:The Philosophy of Rhetoric Source: The Philosophy of Rhetoric
“And as to ordinary metaphors, or those which have already received the public sanction, and which are commonly very numerous in every tongue, the metaphorical meaning comes to be as really ascertained by custom in the particular language as the original, or what is called the literal meaning of the word. And in this respect metaphors stand on the same foot of general use with proper terms.” MetaphorMeaningSanctionsTropes Book:The Philosophy of Rhetoric Source: The Philosophy of Rhetoric