Einstein started a book club, and here's the reading list
What the beloved genius and his buddies discussed in the Olympia Academy is legendary.
'Ethics' by Baruch Spinoza
Baruch Spinoza, a 17th century Dutch philosopher, turned down prestigious teaching positions, choosing instead to spend his days grinding lenses. Lens grinding was a quiet, simple career that, unfortunately, killed him (apparently, breathing blended glass is really bad for your lungs).
Spinoza thought that the universe was made of one substance, so there was no mind-body separation; it was all the same universal gloop. These ideas may have influenced Einstein a good deal; what with the whole "mass and energy are different forms of the same thing" thing.
"Be not astonished at new ideas," wrote Spinoza, "for it is well known to you that a thing does not therefore cease to be true because it is not accepted by many."