In his book ‘The Value of Religion from the Biological Point of View’ Ya. considered the key psychological concepts of his time (E. Starbuck, J. Leuba, W. James, W. Wundt), completing them with Russian examples, and also addressing the issues of philosophy of religion, anthropology, and sociology. As it was typical for the early twentieth century, religious conversion turns out to be one of the central issues studied in the work.

Following the ideas of H. Harald Göffding, Ya. assumed that religion is based on “the striving to affirm (preserve) values”, which is achieved through faith. Noteworthy, ‘the biological point of view’ was understood in the book as scientific psychology, since Ya. Stressed its importance for mental life, both physiology, and milieu and cultural characteristics. In this sense, this work should not be seen in the context of an emerging biological approach to religion; and the consonance with Wesley Wells's 1918 article ‘The Biological Foundations of Religious Faith’ can be assumed as accidental.