In the preparation of this book an attempt has been made to follow the lines of thought – like Ariadne's threads in a maze – leading to our present conception of the mechanism of muscle excitation and contraction, and of the energy provision for it.

It was only in the third century b.c. that Greek observations led to the realisation – rather dimly by Herophilus, quite definitely by Erasistratus – that the muscles were the organs of movement. Erasistratus even suggested a mechanism: the filling of the muscles with pneuma coming through the nerves, and their consequent increase in breadth and diminution in length. We have studied the variants of this theory, still the most important one, in the seventeenth century. We have seen the emphasis laid by Gabriel Fallopius in the early sixteenth century on the significance for movement of the muscle's fibrous structure. Francis Glisson also took a great step forward with his realisation that muscles had an intrinsic irritability independent of the nervous system.

The intensive work in the nineteenth century on the organic chemistry of muscle components and upon catalytic processes had little impact on theories of contraction mechanism; more influential in this direction were the studies of microscopists such as Bowman, Krause and Engelmann. This is apparent in the theories then developed by Pfluger and by Fick.