It’s hard to pick just one, so I’ll go with one I reread recently —Frankenstein by Mary Shelley. It’s not at all like the movies you know. It’s all about what it means to be human. Are humans distinct from nature, or are we part of it? What responsibilities, if any, do we have to other people? Is science just another Tower of Babel, or will it solve all our problems? Pretty deep stuff for a woman still in her teens. Pretty deep stuff for anybody.