Cohn describes the system of Copernicus but rejects it on religious grounds. On the other hand, he enthusiastically supports the Harvey system of blood circulation. At the request of friends from Poland, he deals at length with the disease then common in Poland. He stresses the chemical aspect of stomach diseases, in contrast to the then still prevalent system of Galen. Although Cohn adheres to the old system of medicine, he is fully conscious of new trends, especially in surgery and in chemistry. He applies exact measurements in his scientific work, especially in thermometry. One of Cohn's innovations is the comparison of the human body to a house. The head was the roof, the eyes the windows, and the mouth, the doorway; the chest was the upper storey, the intestines were the middle storey, the lungs were water tanks and the legs, foundations. His remedies were laxatives, emetics, cupping glasses, and bleeding, but he demolished many superstitions and criticized the anti-Jewish professors of Frankfort on the Oder as well as Jews who were devoted to Kabbalah and blindly believed in miracles. His theories relating to infant care and pediatrics were advanced for his age.

Tobias ben Moses Cohn (1652–1729) was a physician and author. His father was a rabbi in Metz who died when Tobias was 9 years old. He was then sent to his relatives in Cracow, where he got a traditional Jewish education. Later he went to Frankfort on the Oder to study medicine. He even got a scholarship from the elector of Brandenburg. He studied at the University of Padua and then went to Turkey where he served as a court physician until the age of 62, when he went to Jerusalem in order to concentrate on the study of Torah.