Language is the main channel in which human beings share the contents of their consciousness. It thereby offers a window into human nature, revealing the hidden workings of our thoughts, our emotions, and our social relationships. I explore an example of each: semantics as a window into human concepts of space, time, substance, and causality; swearing and taboo language as a window into human emotion; and indirect speech—veiled threats and bribes, polite requests, and sexual come-ons—as a window into human social relationships.