Of course it’s always hard to track down quotes whose source text is not English; different translations may use different English words… I had hoped to be able to search the Greek text of the Republic in the Perseus Project for the likely Greek originals of your keywords (sophos, rhetor, stuff like that) but this inexplicably failed. But Ctrl-F plus classics.mit.edu’s edition located the source for me, which I could then map against Perseus to get the proper citation.

I wouldn’t call the patron’s/Emerson’s version a translation so much as a paraphrase, which also adds to the difficulty of tracking it down…