Ideas of this order were irresistibly forced on me by my studies in physiology, of which they seem, indeed, to me to be the necessary consequence. We cannot divide our nature into two portions, and say, This belongs to science, this to religion. No such barrier exists; the attempt to erect one inevitably fails. The study of physical objects is the study of that which is most profoundly spiritual, and must be recognized as being so, if it is to be carried on freely, fully, or to any satisfactory result. Questions relating to our spiritual nature, if not deliberately faced and solved, are sure, consciously or unconsciously, to embarrass all our inquiries: rightly solved, they seem to me to give as great a liberty and vantage-ground to thought, as they impose bondage upon it if they are avoided or falsely conceived. Accepting the idea of a deadness in Man, and a true or spiritual life in Nature, new sources of light opened upon me, and my path seemed to grow clear in almost all directions.

And I have thus briefly indicated the line of thought which led me to it, because I find it at once the fruit and the seed of the scientific knowledge of Nature. Even a slight understanding of the true order of physical phenomena, and of the significance of the physical laws, is sufficient to conduct us to it; from that point it becomes our guide.