Ideas rose in clouds; I felt them collide until pairs interlocked, so to speak, making a stable combination.

Guessing before proving! Need I remind you that it is so that all important discoveries have been made?

A reality completely independent of the spirit that conceives it, sees it, or feels it, is an impossibility. A world so external as that, even if it existed, would be forever inaccessible to us.

In one word, to draw the rule from experience, one must generalize; this is a necessity that imposes itself on the most circumspect observer.

To invent is to discern, to choose.

But for harmony beautiful to contemplate, science would not be worth following.

Mathematical discoveries, small or great are never born of spontaneous generation.