The great need to grasp principles had caused me to spend most of my time on fruitless persuits.
The last thing to collapse is the surface.
Pure mathematics is, in its way, the poetry of logical ideas. ... [By seeking] logical beauty spiritual formulas are discovered necessary for the deeper penetration into the laws of nature.
A little knowledge is a dangerous thing. So is a lot.
One picture is worth a thousand words
I believe that the first step in the setting of a real external world is the formation of the concept of bodily objects and of bodily objects of various kinds.