The quotation from valéry that best expresses what he meant by the “crisis of the mind” that europe experienced after world war i is

“we had long heard tell of whole worlds that had vanished, of empires sunk without a trace, gone down with all their men and all their machines into the unexplorable depths of the centuries . . ”
“never has so much been read, nor with such passion, as during the war: ask the booksellers . . never have people prayed so much and so deeply: ask the priests.”
“the military crisis may be over. the economic crisis is still with us in all its force. but the intellectual crisis, being more subtle and, by its nature, assuming the most deceptive appearances . . this crisis will hardly allow us to grasp its true extent, its phase.”
“no one can say what will be dead or alive tomorrow, in literature, philosophy, aesthetics; no one yet knows what ideas and modes of expression will be inscribed on the casualty list, what novelties will be proclaimed. hope, of course, remains . . ”