... thoroughly intelligible,) some are efficient causes, and some are both together. But of those which have reference to that end, nothing is good except honourable actions; of those which are efficient causes, nothing is good except a friend. But they assert that wisdom is both a referential and an efficient good. For, because wisdom is suitable action, it is of that referential character which I have mentioned; but inasmuch as it brings and causes honourable actions, it may be so far ... — The Academic Questions • M. T. Cicero