•Why it earns a slot
Einstein's own plain-language account of the theory that redefined space and time, proof that the physicist behind one of science's hardest ideas could also explain it without heavy mathematics.
Einstein wrote this book himself to explain relativity to readers with only a general education, no physics degree required. Rather than start with equations, he uses concrete thought experiments, a train, an embankment, two bolts of lightning, to show that ideas physics had always assumed were absolute, like whether two events happen 'at the same time,' actually depend entirely on how fast the observer is moving.
This distillation is written from the freely available original, which is always the better read when you have the time: Project Gutenberg.