"To relate in detail the circumstances, for example, that led St. Albert the Great to describe three methods of contraception belongs to the biographer of St. Albert; all the forces that made Pope Sixtus V decree the penalties of murder for contraception are the domain of the social historian of sixteenth-century Rome. No historian describes all the factors, for he does not know them all; of necessity there is choice and emphasis. Here I have tried to catch the most significant pressures and events that affected the doctrine on contraception. There is an advantage to looking at a single set of concepts over two thousand years."