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.
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.
It is characteristic of fundamental discoveries, of great achievements of the intellect, that they retain an undiminished power upon the imagination of the thinker. The memorable experiment of Faraday with a disc rotating between two poles of a magnet, which has borne such magnificent fruit, has long passed into every-day experience; yet there are certain features about this embryo of the present dynamos and motors which even today appear to us striking, and are worthy of the most careful study.