Life survives by the principle of economy it maintains in itself.
Life is a system of harmony without excess in any of its features. Economic conditions do not exhaust themselves merely in gold and silver, land and property. Economy is the principle of the conservation of life and energy, the proper maintenance of balance in its internally adjusted parts. As the body requires physical exercise, food, water and air as well as light and heat for its healthy continuance, the mind of man, which is more than his body in value, has its own system of economy and balancing of operations. As more than the normal or leas than the normal needs of the body may turn it sick and make it droop in weakness, so can the mind lose its power and become ill by either excessive activity or inactivity.