sentences:  Tang attempted to systematize the moral idealism in his final book Life, Existence, and the Horizons of the Heart-Mind in 1977.He argues that the human heart-mind, the source of cognition, emotion, and will, is key to understanding the world, and that in integrating of reason and emotion, the heart-mind can respond correctly in a given situation.The other main point of this book is the Nine Horizons, the spheres of existence that human activity engages with.