I realize that..

..it is getting to be late in the calendar year and I have yet to compile quotations about mediocrities in this space.  My most sincere apologies.

Nothing is as approved as mediocrity, the majority has established it and it fixes its fangs on whatever gets beyond it either way.
-Blaise Pascal

Only mediocrity can be trusted to be always at its best.
-Max Beerbohm

Most of our pocket wisdom is conceived for the use of mediocre people, to discourage them from ambitious attempts, and generally console them in their mediocrity.
-Robert Louis Stevenson

The middlebrow is the man, or woman, of middlebred intelligence who ambles and saunters now on this side of the hedge, now on that, in pursuit of no single object, neither art itself nor life itself, but both mixed indistinguishably, and rather nastily, with money, fame, power, or prestige.
-Virginia Woolf

Perseverance, n. A lowly virtue whereby mediocrity achieves an inglorious success.
- Ambrose Bierce

Ridicule is the tribute paid to the genius by the mediocrities.
-Oscar Wilde

Mediocrity is not allowed to poets, either by the gods or man. -Horace

There are certain things in which mediocrity is intolerable: poetry, music, painting, public eloquence. What torture it is to hear a frigid speech being pompously declaimed, or second-rate verse spoken with all a bad poet's bombast!
-Jean de la Bruyere

Mediocrity is now, as formerly, dangerous, commonly fatal, to the poet; but among even the successful writers of prose, those who rise sensibly above it are the very rarest exceptions.
-William E. Gladstone

In the dark room a cloud of yellow dust flew from beneath the tool like a scatter of sparks from under the hooves of a galloping horse. The twin wheels turned and hummed. Binet was smiling, his chin down, his nostrils distended. He seemed lost in the kind of happiness which, as a rule, accompanies only those mediocre occupations that tickle the intelligence with easy difficulties, and satisfy it with a sense of achievement beyond which there is nothing left for dreams to feed on.
-Flaubert