labourer with his spade, surely exercises a power that has no relation to the sun. Is not volition a power altogether distinct from material force? Does not the will create force? Science, however, clearly shews that this is no exception to the general rule. The body is to man what the coals are to the steam-engine. The mind may direct, but it cannot create. And every time that a man strikes a blow with a hammer, he as surely wastes a certain amount of physical force stored up in his body as every stroke of the piston in a steam-engine wastes a certain amount of coals in the furnace. The waste of tissues in the body corresponds to the combustion of coals in the furnace. But whence the power stored up in these tissues? The answer is, from the sun. All animal structures can be ultimately traced to vegetable food; and the vegetable world is only the storehouse of the force emanating from the sun. The only force existing on the face of the earth not traceable directly to the sun is that of the tides. The tides would exist if the fluidity of the ocean could be maintained, even though the heat of the sun was extinguished. The trade winds are also in part independent of the sun, the direction being due to the rotation of the earth. These, however, form but insignificant exceptions to the general rule, that the power available for the purposes of man can be traced to the sun as the great source.
The sun, then, is the great worker, and the slave
