Seen here is the cover of a work titled “The Book About Marriage. The Sexual Life of the Human Being. With 39 Anatomical Drawings” by Dr. O. Retau, published in 1900.
The moral code of Wilhemine society — the German parallel to England’s Victorian society — viewed sex as something that should only occur within marriage. This book was designed to give the latest scientific and medical information on how sexual intercourse, conception, pregnancy and birth work. But it also contained much more (see the Table of Contents).