We are concerned with the problem of man because he is a being afflicted with contradictions and perplexities, because he is not completely a part of his environment. A good horse, properly cared for, lives as a part of his habitat and is unencumbered by problems. In sharp contrast, man is a problem intrinsically and under all circumstances. To be human is to be a problem, and the problem expresses itself in anguish, in the mental suffering of man.

A.J. Heschel. Who is Man ? Stanford U Press, p 3