Page:Divine Selection or The Survival of the Useful.djvu/70

 that is not in harmony with physical facts. We need not accept anything that is not similar to that with which we are already familiar. In fact the very opposite is imperative. We are requested to think in harmony with physical facts; to reason just as we do about things with which we are familiar, and to disbelieve everything that is not in harmony with a broad and true conception of nature and her laws.

We know how the sun imparts activity to nature and fills it with sun potencies. We are continually impressed with the complex and numerous forms of the activity of ether as displayed by the prism and photography. If there are so many varieties of electric activity that there are developed not only such different things as heat, light, and power, but also many particular activities, exemplified by the X-ray, wireless telegraphy, and radio activity in general, how much more probable it is