Founding a Science of the Spirit by Rudolf Steiner
These lectures offer a fine introduction to the whole of Steiner's teaching. He speaks of the fundamental nature of the human being in relation to the cosmos, the evolution of the Earth, the journey of the soul after death, reincarnation and karma, good and evil, the modern path of meditative training, as well as giving answers to individual questions.
Throughout the text, Steiner emphasizes the scientific exposition of spiritual phenomena. As he says in his final lecture, "The highest knowledge of mundane things is thoroughly compatible with the highest knowledge of spiritual truths."