I love books and knowledge. Tough to pick a favorite amongst secular concerns, but my all-time favorite is the Bible. Deep, poignant, compelling--full of motivation, greed, betrayal, faith, comradeship and most of all love.
In mathematics, "Calculus Made Easy," by Sylvanus P. Thompson, because he was brave enough to call "bad" the so-called education of mathematicians who did more to attempt to impress each other than to illuminate the minds of youngsters.
In science, "Guns, Germs and Steel," by Jared Diamond. A compelling look at the possible foundations of civilization.
In fiction literature, "Dune," by Frank Herbert. A story full of motivation, passion and faith.
Of course, I'm also partial to one I co-authored with a friend: "Touch the Stars: Emergence," with John Dalmas (pen name, Carl Martin). And one by my Dad (Rod Martin) and John Dalmas: "The Playmasters."