I have not yet even been able to prove rigorously that my axioms   are “consistent”, though this is certainly very   essential; instead I have had to confine myself to pointing out now   and then that the “antinomies” discovered so far vanish   one and all if the principles here proposed are adopted as a   basis. But I hope to have done at least some useful spadework hereby   for subsequent investigations in such deeper problems. (1908b:   262)