9. The course of biological speculation has been similar to the cosmological. It also began with a First Notion, which compendiously expressed the facts of Experience. Nor can any Theoretic Conception be finally adopted which does away with these facts, known with positive certainty, and popularly expressed in the phrase: “I have a body, and a soul.” We may alter the phrase either into “I _am_ a body, and I _am_ a soul”; or into, “My body is only the manifestation of my soul”; or, “My soul is only a function of my body”; but the fundamental experiences which are thus expressed are of absolute authority, no matter how they may be interpreted. That I have a body, or am a body, is not to be speculatively argued away. That I move my arm to strike the man who has offended me, or stretch out my hand to seize the fruit which I see, is unquestionable; that these movements are determined by these feelings, and are never thus effected unless thus determined, is also unquestionable. Here are two sets of phenomena, having well-marked differences of aspect; and they are grouped respectively under two general heads, Life and Mind. Life is assigned to the physical organism, or Body--all its phenomena are objective. Mind is assigned to the psychical organism, or Soul--all its phenomena are subjective. Although what is called my Body is shown to be a group of qualities which are feelings--its color, form, solidity, position, motion--all its physical attributes being what is felt by us in consequence of the laws of our organization; yet inasmuch as these feelings have the characteristic marks of objectivity, and are thereby referred to some objective existence, we draw a broad line of demarcation between them and other feelings having the characteristic marks of subjectivity, and referring to ourselves as subjects. Psychological analysis shows us that this line of demarcation is artificial, only representing a diversity of aspect; but as such it is indispensable to science. We cannot really separate in a sensation what is objective from what is subjective, and say how much belongs to the Cosmos apart from Sensibility, and how much to the subject pure and simple; we can only view the sensation alternately in its objective and subjective aspects. What belongs to extra-mental existence in the phenomenon of Color, and what to the “greeting of the spirit,” is utterly beyond human knowledge: for the ethereal undulations which physicists presuppose as the cosmic condition are themselves subjected to this same greeting of the spirit: they too are ideal forms of sensible experiences.