S1:          Our ancestors thought that anything which moved itself was alive. P :           The philosopher Descartes thought that both men and animals were machines. Q :          But a machine such as a motorcar or a steamship moves itself, as soon as machines which moved themselves had been made, people asked “Is man a machine?” R :          And before the days of machinery that was a good definition. S :           He also thought that the human machine was partly controlled by the soul action on a certain part of the brain, while animals had no souls. S6:          Therefore some scientists think that life is just a very complicated mechanism. The Proper sequence should be: