ANAL'OGY, noun [Gr. ratio, proportion.]
1. an agreement or likeness between things in some circumstances or effects, when the things are otherwise entirely different. Thus a plant is said to have life, because its growth resembles in some degree, that of an animal. In life and growth, then, there is an analogy between a plant and an animal. Learning enlightens the mind, because it is to the mind, what light is to the eye, enabling it to discover things before hidden. When the things which have an analogy follow a preposition, that preposition must be between or betwixt; as there is an analogy between plants and animals, or between customs. When one of the things precedes a verb, and the other follows, the preposition used must be to or with; as, a plant has some analogy to or with an animal.
2. With grammarians, analogy is a conformity of words to the genius, structure or general rules of a language. Thus the general rule in English is that the plural of a noun ends in es; therefore all nouns which have that plural termination have an analogy or are formed in analogy with other words of a like kind.
[PUBLISHERS NOTE: The word "genius" in the second definition should be "genus". This appears in the original printing and is most likely a printers error as the original was hand typeset.]