Physics and Politics, or, Thoughts on the application of the principles of "natural selection" and "inheritance" to political society

The Philosophy of the Moral Feelings

The Biology, Physiology and Sociology of Reproduction / Also Sexual Hygiene with Special Reference to the Male

The Psychology of Nations / A Contribution to the Philosophy of History

The Book of Religions / Comprising the Views, Creeds, Sentiments, or Opinions, of All the Principal Religious Sects in the World, Particularly of All Christian Denominations in Europe and America, to Which are Added Church and Missionary Statistics, Toget

Ten Great Religions / An Essay in Comparative Theology