The search for something permanent is one of the deepest of the instincts leading men to philosophy.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“I shall return to the consideration of this doctrine in connection with Plato, who is much concerned to refute it. For the present, I shall not investigate what philosophy has to say about it, but only what the poets have felt and the men of science have taught. The search for something permanent is one of the deepest of the instincts leading men to philosophy. It is derived, no doubt, from love of home and desire for a refuge from danger; we find, accordingly, that it is most passionate in those whose lives are most exposed to catastrophe. Religion seeks permanence in two forms, God and immortality.” source