Since several geometries are possible, is it certain ours is the true one? - Henri Poincaré

Most striking at first is this appearance of sudden illumination, a manifest sign of long, unconscious prior work. The role of this unconscious work in mathematical invention appears to me incontestable.

La pensée n'est qu'un écliar au milieu d'une longue nuit. Mais c'est cet éclair qui est tout.

Thought is only a flash in the middle of a long night. But this flash means everything.

Is not my present nearer my past of yesterday than the present of Sirius?