trace, but would nevertheless be as precise and invariable as before; and we should know that if we artificially changed the position of one, we should in definite proportions change the positions of the others. So it is in society, only the mechanism is so much more complicated as to defy the same complete observation and precise calculation.

In taking a rough view of a social state, we should find so many people living on so many square miles, so many varieties of occupation, so much education, so much ignorance, so much wealth distributed with certain inequalities, political power residing in a larger or smaller portion of the community, so much pauperism, and so much crime. The connection between some of these phenomena would be causal-that is to say, that one would be an invariable sequence of the other-while between others the connection would be accidental or casual. To give an example of each-typhus fever would always be found in dirty, crowded streets, loaded with decomposing animal matter, and the decomposing filth would be shown to be the cause of the fever. To illustrate a casual connection, it may be remarked that in the present state of England and France, suicides abound most in districts where there is least

ignorance; but ignorance is not the cause of their comparative absence in one case or presence in another. The connection is accidental, and probably arises from the fact that the aggregation of men in large capitals affords great facilities for the increase and diffusion of knowledge, and at the same time keeps the nervous system at its greatest tension, and furnishes the most complete misery for those who are unsuccessful in the race of life. Social statics would be of no use except to gratify curiosity if society were not susceptible of change; but, as the matter stands, a knowledge of social statics leads us to a dynamical law, and we learn that if we could alter the condition of one portion, what changes would follow in the condition of the rest.

Social dynamics, as before observed, has to investigate the law of the sequence of social · phenomena; some of its most interesting branches are those which trace the growth and change of speculative opinion, and the corresponding modifications of government and institutions which are thereby produced.

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CHAPTER VI.

THE LAW OF EXERCISE, AND ITS DERIVATIVES.

IF a muscle is not exercised it shrinks and dwindles from the consequent depression of its faculty of nutrition, and after a time loses the characteristic property of its ultimate fibrescontractility. On the other hand, exercise, within certain limits, increases its power of nutrition, and also its contractility, so that it grows larger and becomes stronger. Similar observations may be made with reference to nervous tissues and the brain, the condition of which is inseparably connected with every manifestation of intellectual or moral faculties that occur in this mortal life. The law of exercise is not a primary law, because the effects of exercise, or the want of it, are dependent upon laws of a more ultimate and general kind, but it is one of the most important of all the secondary laws by which the condition of humanity is ruled. It not only regulates the physical

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development, but also the mental; for every
mental action is attended by a physical change.
Every thought or emotion is associated with an
action of the nervous substance of the brain, and
every act of the nervous system involves the
death and decay of a certain amount of nervous
matter, the replacement of which will be requisite
in order to maintain the system in a state fit for
action." *
So close is the connection between
mental and physical action, that an unusual waste
of nervous tissue, marked by increased secretion
of phosphates derived from its structure, always
accompanies severe exercise of the brain; and
where increased cerebral action is periodical, as in
the case of clergymen, the kidneys at such times
eliminate a larger quantity of phosphatic salts.†
Thus exercise is indispensable to growth, or to the
maintenance of the power of human organs or
faculties; and it is equally essential to the
acquisition of facility, whether in muscular move-
ments, or subtle combinations of thought. It is
only by continual exercise that the musician is
able to execute the rapid combinations and succes-
sions of finger motion employed in performing
upon his instrument, and it is by means precisely

*Carpenter. Manual of Physiology,' Sec. 384.
† Ibid. 386.

similar that facilities are acquired for observation, experiment, and philosophical thought, or for the exercise of fancy, or the employment of the emotional powers. If men had few muscular and other physical faculties, a very limited range of exercises would suffice for their development; and, in like manner, if they had few mental and moral faculties, a small variety in surrounding circumstances would afford all the opportunity needed for their growth. Such, however, is not the case: the physical and mental faculties of man are numerous, and demand an immense variety of conditions for their appropriate manifestation. In the town life of civilized countries a host of diseases and debilities arise entirely for want of circumstances that permit the healthy exercise of physical powers, while the surroundings of the moral and intellectual life of the most favoured communities leave much to be desired in the way of greater facilities for the employment of the higher powers of the human mind.

We have not yet arrived at a satisfactory enumeration of the simple faculties of the human mind, but the phrenological division-though evidently provisional-affords a good idea of their number and variety. Were this division and enumeration correct, we should not only require