Machiavelli is not concerned with how men do live merely in order to describe it; his intention is rather, on the basis of knowledge of how men do li… - Leo Strauss

The character, or tone, of a society depends on what the society regards as the most respectable or most worthy of admiration. But by regarding certain habits or attitudes as most respectable, a society admits the superiority, the superior dignity, of those human beings who most perfectly embody the habits or attitudes in question. That is to say, every society regards a specific human type (or a specific mixture of human types) as authoritative. When the authoritative type is the common man, everything has to justify itself before the tribunal of the common man; everything which cannot be justified before that tribunal becomes, at best, merely tolerated, if not despised or suspect. And even those who do not recognize that tribunal are, willy-nilly, molded by its verdicts.

Men are constantly attracted and deluded by two opposite charms: the charm of competence which is engendered by mathematics and everything akin to mathematics, and the charm of humble awe, which is engendered by meditation on the human soul and its experiences. Philosophy is characterized by the gentle, if firm, refusal to succumb to either charm. It is the highest form of the mating of courage and moderation. In spite of its highness or nobility, it could appear as Sisyphean or ugly, when one contrasts its achievement with its goal. Yet it is necessarily accompanied, sustained and elevated by eros. It is graced by nature's grace.

Existentialism is a 'movement' which like all such movements has a flabby periphery and a hard center. That center is the thought of Heidegger.