I am reading “Natural Right and History” by Leo Strauss and I have trouble to understand the following quote (Chapter 2, Paragraph 2):
If philosophy in general is possible, political philosophy in particular is possible. Political philosophy is possible if man is capable of understanding the fundamental political alternative which is at the bottom of the ephemeral or accidental alternatives.
I am not sure if the second sentence is a short characterisation of the fundamental political alternative telling me that I can recognise this alternative as the one lying at the bottom of the two others, or if it is merely a reference to a common background I do not have—I come from mathematics.
What are the political, ephemeral and accidental alternatives which Leo Strauss is here referring to? How should I understand the relation between them that the quoted text displays?