One should not pursue goals that are easily achieved. One must develop an instinct for what one can just barely achieve through one’s greatest efforts.
I don't think necessity is the mother of invention. Invention, in my opinion, arises directly from idleness, possibly also from laziness - to save oneself trouble.
It is true that the grasping of truth is not possible without empirical basis. However, the deeper we penetrate and the more extensive and embracing our theories become the less empirical knowledge is needed to determine those theories.
By an epiphany he meant a sudden spiritual manifestation, whether in the vulgarity of speech or of gesture or memorable phrase of the mind itself. He believed it was for the man of letters to record these epiphanies with extreme care (saving them for later use, that is), seeing that they themselves are the most delicate and evanescent of moments.