"This shifting of weight from monopoly to efficiency explanations as the primary motive for a business practice has, I think, been permanent among economists and policy makers. This broader change in the framework of our analysis owes much to Aaron Director. It may be his most important intellectual legacy."
That's Sam Peltzman on Aaron Director in the latest issue of Journal of Law and Economics.
Also in the same issue, there is another piece on Aaron by Stephen Stigler, the son of George Stigler.