Avant-propos.--Les principes de la morale positiviste et la conscience contemporaine, par G. Belot.--La morale de Renouvier, par A. Darlu.--La morale de Bastiat, par Ch. Gide.--La morale de Proudhon, par M. Bernès.--Karl Marx, par A. Landry.--Les idées morales de Vinet, par J.-E. Roberty.--La morale et la politique de Renan, par R. Allier.--Frédéric Nietzsche, par H. Lichtenberger.--Maurice Mæterlinck, par L. Brunschvicg.

This essay revisits some classic problems in the philosophy of space and time concerning the counting of possibilities. I argue that we should think that two Newtonian worlds can differ only as to when or where things happen and that general relativistic worlds can differ in something like the same way—the first of these theses being quaintly heterodox, the second baldly heretical, according to the mores of contemporary philosophy of physics.