Yes, it is referenced a lot. Possible answer: Plato Phaedo. He’s quoting Socrates, and it goes “living round our sea like ants or frogs round a pool (some translate it marsh)…” But I know I’ve seen the other quote you wrote somewhere. Edit: this may not be correct. Phaedo doesn’t go up that high and ‘frog’ doesn’t appear in it when a search is done. http://www.san.beck.org/Phaedo.html or google books version
FAVORED beyond all other great waters by climate and position, this million-square-mile sea of coves and arms and islets is made to man's measure. “Like frogs around a pond,” said Plato, “we have settled down upon the shores of this sea.” Island-hopping along Aegean shores in the haze of lazy, sunlit waters, the Phoenicians and Greeks of 30 centuries ago first learned the arts of maritime commerce, and of naval war?including the amphibious landing.http://www.time.com/time/magazine/article/0,9171,891750,00.html By the time of Aristotle (fourth century BC) there were hundreds of Greek democracies. Greece in those times was not a single political entity but rather a collection of some 1,500 separate poleis or 'cities' scattered round the Mediterranean and Black Sea shores 'like frogs around a pond', as Plato once charmingly put it.http://www.bbc.co.uk/history/ancient/greeks/greekdemocracy_01.shtml