http://www.godecookery.com/tacuin/tacuin.htm .

"IX. Coitus (Coytus) Nature: It is the union of two for the purpose of introducing the sperm. Optimum: That which lasts until the sperm has been completely emitted. Usefulness: It preserves the species. Dangers: It is harmful to those with cold and dry breathing. Neutralization of the Dangers: With sperm-producing foods."