S. Austin Allibone, comp. Prose Quotations from Socrates to Macaulay. 1880.
How many of these minds are there to whom scarcely any good can be done! They have no excitability. You are attempting to kindle a fire of stones. You must leave them as you find them, in permanent mediocrity. You waste your time if you do not employ it on materials which you can actually modify, while such can be found. I find that most people are made only for the common uses of life.
Among many parallels which men of imagination have drawn between the natural and moral state of the world, it has been observed that happiness, as well as virtue, consists in mediocrity; that to avoid every extreme is necessary, even to him that has no other care than to pass through the present state with ease and safety; and that the middle path is the road of security, on either side of which are not only the pitfalls of vice, but the precipice of ruin.
Thus the maxim of Cleobulus, the Lindian, [Greek], Mediocrity is best, has been long considered a universal principle, extended through the whole compass of life and nature. The experience of every age seems to have given it new confirmation, and to show that nothing, however specious or alluring, is pursued with propriety, or enjoyed with safety, beyond certain limits.