434 Longevity of Brain-Workers. [October, 
Causes of the Great Longevity of Brain- Workers. 
The full explanation of the superior longevity of the brain- 
working classes would require a treatise on the science of 
sociology, and particularly of the relation of civilisation to 
health. The leading factors, accounting for the long life of 
those who live by brain-labour, are as follows :— 
1. The inherent and essential healthfulness of brain-work. To 
work is to grow; and growth, except it be forced, is always 
healthful. It is as much the function of the brain to cere- 
brate as of the stomach to digest; and cerebration, like 
digestion, is normal, physiological, and healthful. In all 
organisations of force the exercise of force develops more 
force; work evolves strength for work. A plant that is 
suffered to bud and bloom is more sturdy and longer lived 
than the plant that is kept from the light or trimmed of all 
its blossoms, By thinking, we gain the power to think ; 
functional activity, within limits, tends to vigour and the 
self-preservation of an organ and of the body to which the 
organ belongs. The world has been taught that the brain 
can be developed only at the expense of the other organs of 
the body; granting that brain-work strengthens the brain 
itself, the rest of the body is impoverished thereby—hence 
disease, and early death. But recent investigations in 
cerebro-physiology seem to indicate that the centres of 
thought in the anterior region of the brain are also the 
centres of muscular motion; and hence it may perhaps be 
inferred that to develop the brain may be one method of 
developing the muscles.* Ic is certain that the brain-working 
classes are, on the average, well developed muscularly ; and 
in size and weight are superior to the purely muscle-working 
classes. 
2. Brain-workers have less worry, and more comfort and 
happiness, than muscle-workers. Worry is the converse of 
work; the one develops force, and the other checks its 
development, and wastes what already exists. Work is’ 
growth ; worry is interference with growth. Worry is to 
work what the chafing of a plant against the walls of a 
* I here refer to the experiments of Hitzig, of Berlin, in the eleétrical 
irritation of the brains of living animals. These experiments have been con- 
firmed by a variety of experiments undertaken by Ferrier, of London, by 
myself, and other observers. I use the word centre, in an experimental sense ; 
and the above theory of the relation and definition of the thought centres, and 
muscle centres, is merely a provisional suggestion. (See ‘‘ Archives of Electro- 
logy and Neurology,’’ May, 1874, for a record of my own experiments, with 
remarks, and also a general resumé of facts). 
