The Gods Themselves - I'm a definitely a fan of Asimov -- his creativity and prolificness is so impressive. The Robot and Foundation series' are certainly my favorites. I received The Gods Themselves from a bookseller I'd bought a collection of Hemingway's journalism from. He threw in a paperback of The Gods Themselves along with a couple other gifts (thanks @kayoulerarebooks!). I'd never heard of the novel, but the cover of the version he sent proclaims that it received "Best Science Fiction Novel of the Year Award" and, according to the back cover, the Philadelphia Bulletin declared it to be "A tour de force unlike anything Asimov has done before...The Gods Themselves is definitive science fiction...well worth reading," and according to Wikipedia it was Asimov's favorite sci fi novel. So I picked it up.