From Robert Louis Stevenson's essay *An Apology for Idlers* (1881). Select the word that fits the blank. "This is not the moment to ______ on that mighty place of education, which was the favourite school of Dickens and of Balzac, and turns out yearly many inglorious masters in the Science of the Aspects of Life."

*This is not the moment to ______ on* sets up the blank as a verb meaning *to expand at length on a subject*. Stevenson is acknowledging a topic he could discuss in more detail but choosing not to do so now. "Dilate" — in this sense, *to speak or write at length on a subject; to expand* — is the precise verb. The same root that gives us the physical sense (*to dilate the pupils*, to make them wider) gives the figurative sense (*to dilate on a topic*, to enlarge upon it). The literary sense is older and is the one Stevenson uses. - "Dwindle" goes in the wrong direction (decrease). - "Retreat" doesn't fit the *to ______ on* construction. - "Interfere" doesn't fit semantically. The physical and figurative senses of *dilate* share the same root meaning — *to widen out* — and the figurative one is GRE-canonical: *to dilate upon* a subject is to expand a discussion of it.