Nor can it account for, or even follow with any degree of precision, the stages of transformation leading from apparent uniformity of structure to diversity of organization. The origin of life, and the conditions which have gradually given rise to organization, are essential evolutional moments, as yet in the twilight of mere fanciful conjecture. Their penetration and elucidation would yield the data for the solution of what may be called the physical phase of the problem of life.
But, further on, in pursuance of evolutional continuity, we encounter a still deeper mystery, separating most profoundly the world of matter from the world of mind. We are all aware that this strange contrast of matter and thought, of the extended and the inextended, has ever constituted a fundamental dualism in human experience. Philosophy in every one of its aspects is mainly the result of an effort to imagine or to recognize the connection which necessarily must obtain between the ideal and the real. But there has been far too much imagining, and too little recognition, in the endeavor. So, till quite lately, in the history of human thought, but very slight advance was made in the solution of the central puzzle, concerning ideality and reality. Modern Science, disgusted at the waste of so much precious energy and earnestness, given up to the elaboration of mere whimsical and visionary interpretations, set out with the positive intention to evade in its investigations any contact with this constant stumbling-block of certitude. But the antagonistic powers of outwardness and inwardness are too intimately blended in Nature to admit of any such artificial severance, however skillfully attempted.
Scientists are becoming more and more conscious that, even in their least complicated suppositions and inquiries, both those elements of the actual world are always inextricably involved. Before the steadfast glance of Science, the eternal, adamantine atoms, questioned as to the essence of their subsistence and resistance, dissolve into unextended, immaterial centres of force. Before the steadfast glance of Science, the inscrutable forces, with their ideal sweep, traced to the immediate seat of their activity, resolve themselves into the discrete multiplicity and absolute impenetrability of adamantine atoms. Surely, if with witches "fair is foul and foul is fair," with us benighted mortals confusion seems to reign still more supreme, for, to our profoundest thinkers, matter is force and force is matter; motion somehow is sensation, and sensation somehow motion. And yet how can we aspire ever clearly to comprehend the fundamental identity of such disparate manifestations as matter and mind?
Naturalists are aware of and openly acknowledge this mysterious polarity of phenomena, this double subsistence—one in reality and at the same time also in ideality. To the former mode of existence they give the name of motion, the latter they call sensation—motion being the generalized fact of outwardness, of objectivity; sensation being the generalized fact of inwardness, of subjectivity.
