[H]e (Socrates) thus implies that there is a parallelism between the city and the human individual or, more precisely, between the city and the soul … - Leo Strauss

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

The adjective “political” in “political philosophy” designates not so much the subject matter as a manner of treatment; from this point of view, I say, “political philosophy” means primarily not the philosophic study of politics, but the political, or popular, treatment of philosophy, or the political introduction to philosophy—the attempt to lead qualified citizens, or rather their qualified sons, from the political life to the philosophic life.

Philosophy as such is nothing but genuine awareness of the problems, i.e., of the fundamental and comprehensive problems. It is impossible to think about these problems without becoming inclined toward a solution, toward one or the other of the very few typical solutions. Yet as long as there is no wisdom but only quest for wisdom, the evidence of all solutions is necessarily smaller than the evidence of the problems. Therefore the philosopher ceases to be a philosopher at the moment at which the 'subjective certainty' [quoting M. Alexandre Kojève] of a solution becomes stronger than his awareness of the problematic character of that solution. At that moment the sectarian is born. The danger of succumbing to the attraction of solutions is essential to philosophy which, without incurring this danger, would degenerate into playing with the problems. But the philosopher does not necessarily succumb to this danger, as is shown by Socrates, who never belonged to a sect and never founded one. And even if the philosophic friends are compelled to be members of a sect or to found one, they are not necessarily members of one and the same sect: Amicus Plato.