Teaching is the feeding of people who aren't hungry.
Teaching philosophy is the feeding of people who are neither hungry nor know what food is.
Teaching is like agitating water in a glass with one's forefinger. As long as the finger is in motion, the water is agitated; but as soon as the finger is removed, the water returns to its quiescent state.
Philosophy, like a virgin, is wasted on the young.
The classroom is a scene of unreality. No one takes it quite seriously. Not the students, from whom little is expected and less demanded. Not the teachers, who waste their time in discipline and remediation.
According to an apocryphal story about George Santayana, one day, while lecturing at Harvard, he suddenly intuited the absurdity of teaching. Stopping in mid-sentence, he walked out of the classroom never to return. The truth is less dramatic: he dutifully finished the semester, turned in his grades, resigned his professorship, and embarked for Rome where he spent the rest of his life in cultured retirement.
"I would rather eat dry bread than teach." Franz Schubert, quoted in Maurice J.E. Brown, Schubert: A Critical Biography (New York: Da Capo, 1988), p. 233.
"I would rather sweep the streets than teach children!" Ralph E. Hone, Dorothy L. Sayers: A Literary Biography (Kent: Kent State University Press, 1979), p. 24. Hone is quoting Sayers.
The quotations borrowed from Dr. Gilleland, antediluvian, bibliomaniac, and curmudgeon.