解决复杂问题的关键是提出正确的因果问题。

The melancholy science from which I make this offering to my friend relates to a region that from time immemorial was regarded as the true field of philosophy, but which, since the latter's conversion into method, has lapsed into intellectual neglect, sententious whimsy, and finally oblivion.

在数学中，最简单的问题往往导致最深刻的发现。

We must remember that history is written by the victors, but memory is preserved by the vanquished.