Later generations will regard Mengenlehre (set theory) as a disease from which one has recovered. - Henri Poincaré

But these labels can only be finite in number. On that score, psychologic time should be discontinuous.

What I do see is that the sensations which correspond to movements in the same direction are connected in my mind by a mere association of ideas. It is to this association that what we call 'the sense of direction' is reducible. This feeling therefore can not be found in a single sensation

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.