The Beautiful / An Introduction to Psychological Aesthetics

Taboo and Genetics / A Study of the Biological, Sociological and Psychological Foundation of the Family

A Text-Book of Astronomy

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

The Mystic Will. A Method of Developing and Strengthening the Faculties of the Mind, through the Awakened Will, by a Simple, Scientific Process Possible to Any Person of Ordinary Intelligence

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

Three Philosophical Poets / Lucretius, Dante, and Goethe

Five Stages of Greek Religion

Mental Efficiency / And Other Hints to Men and Women

Christianity and Greek Philosophy / or, the relation between spontaneous and reflective thought / in Greece and the positive teaching of Christ and His / Apostles