>Mathematics, as we know it, appears to us as one of the necessary forms of our thought. fhe archaeologist and the historian have shown us civilizations from which mathematics were absent. It is indeed doubtful whether they would ever have become more than a technique, at the service of technologies, if it had not been for the Greeks; and it is possible that, under our very eyes, a type of human society is being evolved in which they will be nothing but that. But for us, whose shoulders sag under the weight of the heritage of Greek thought and who walk in the paths traced out by the heroes of the Renaissance, a civili- zation without mathematics is unthinkable. Like the parallel postulate, the postulate that mathematics will survive has been stripped of its “evidence”; but, while the former is no longer necessary, we would not be able to get on without the latter.