Words, Shading Off Into One Another

"In the infancy of logic, men sought only to obtain a definition of an unknown or uncertain term; the after reflection scarcely occured to them that the word might have several senses, which shaded off into one another, and were not capable of being comprehended in a single notion. There is no trace of this reflection in Plato."

From Benjamin Jowett's introduction to Plato's Sophist...