Without a strategic retreat into the self, without vigilant thought, human life is impossible. Call to mind all that mankind owes to certain great withdrawals into the self! It is no chance that all the great founders of religions preceded their apostolates by famous retreats. Buddha withdraws to the forest; Mahomet withdraws to his tent, and even there he withdraws from his tent by wrapping his head in his cloak; above all, Jesus goes apart into the desert for forty days.