  If there is a "platonic world" M of mathematical facts, what does M contain
precisely? I observe that if M is too large, it is uninteresting, because the
value is in the selection, not in the totality; if it is smaller and
interesting, it is not independent from us. Both alternatives challenge
mathematical platonism. I suggest that the universality of our mathematics may
be a prejudice hiding its contingency, and illustrate contingent aspects of
classical geometry, arithmetic and linear algebra.
