16. No idea of abstract substance either in body or spirit. By the complex idea of extended, figured, coloured, and all other sensible qualities, which is all that we know of it, we are as far from the idea of the substance of body, as if we knew nothing at all: nor after all the acquaintance and familiarity which we imagine we have with matter, and the many qualities men assure themselves they perceive and know in bodies, will it perhaps upon examination be found, that they have any more or clearer primary ideas belonging to body, than they have belonging to immaterial spirit.
17. Cohesion of solid parts and impulse, the primary ideas peculiar to body. The primary ideas we have peculiar to body, as contradistinguished to spirit, are the cohesion of solid, and consequently separable, parts, and a power of communicating motion by impulse. These, I think, are the original ideas proper and peculiar to body; for figure is but the consequence of finite extension.
18. Thinking and motivity the primary ideas peculiar to spirit.
The ideas we have belonging and peculiar to spirit, are thinking, and will, or a power of putting body into motion by thought, and, which is consequent to it, liberty. For, as body cannot but communicate its motion by impulse to another body, which it meets with at rest, so the mind can put bodies into motion, or forbear to do so, as it pleases. The ideas of existence, duration, and mobility, are common to them both.
19. Spirits capable of motion. There is no reason why it should be thought strange, that I make mobility belong to spirit; for having no other idea of motion, but change of distance with other beings that are considered as at rest; and finding that spirits, as well as bodies, cannot operate but where they are; and that spirits do operate at several times in several places, I cannot but attribute change of place to all finite spirits: (for of the Infinite Spirit I speak not here). For my soul, being a real being as well as my body, is certainly as capable of changing distance with any other body, or being, as body itself; and so is capable of motion. And if a mathematician can consider a certain distance, or a change of that distance between two points, one may certainly conceive a distance, and a change of distance, between two spirits; and so conceive their motion, their approach or removal, one from another.
20. Proof of this. Every one finds in himself that his soul can think, will, and operate on his body in the place where that is, but cannot operate on a body, or in a place, an hundred miles distant from it. Nobody can imagine that his soul can think or move a body at Oxford, whilst he is at London; and cannot but know, that, being united to his body, it constantly changes place all the whole journey between Oxford and London, as the coach or horse does that carries him, and I think may be said to be truly all that while in motion: or if that will not be allowed to afford us a clear idea enough of its motion, its being separated from the body in death, Ithink, will; for to consider it as going out of the body, or leaving it, and yet to have no idea of its motion, seems to me impossible.
21. God immoveable, because infinite. If it be said by any one that it cannot change place, because it hath none, for the spirits are not in loco, but ubi; I suppose that way of talking will not now be of much weight to many, in an age that is not much disposed to admire, or suffer themselves to be deceived by such unintelligible ways of speaking. But if any one thinks there is any sense in that distinction, and that it is applicable to our present purpose, Idesire him to put it into intelligible English; and then from thence draw a reason to show that immaterial spirits are not capable of motion. Indeed motion cannot be attributed to God; not because he is an immaterial, but because he is an infinite spirit.
22. Our complex idea of an immaterial spirit and our complex idea of body compared. Let us compare, then, our complex idea of an immaterial spirit with our complex idea of body, and see whether there be any more obscurity in one than in the other, and in which most. Our idea of body, as I think, is an extended solid substance, capable of communicating motion by impulse: and our idea of soul, as an immaterial spirit, is of a substance that thinks, and has a power of exciting motion in body, by willing, or thought. These, I think, are our complex ideas of soul and body, as contradistinguished; and now let us examine which has most obscurity in it, and difficulty to be apprehended. I know that people whose thoughts are immersed in matter, and have so subjected their minds to their senses that they seldom reflect on anything beyond them, are apt to say, they cannot comprehend a thinking thing, which perhaps is true: but I affirm, when they consider it well, they can no more comprehend an extended thing.
23. Cohesion of solid parts in body as hard to be conceived as thinking in a soul. If any one says he knows not what it is thinks in him, he means he knows not what the substance is of that thinking thing: No more, say I, knows he what the substance is of that solid thing. Further, if he says he knows not how he thinks, I answer, Neither knows he how he is extended, how the solid parts of body are united, or cohere together to make extension. For though the pressure of the particles of air may account for the cohesion of several parts of matter that are grosser than the particles of air, and have pores less than the corpuscles of air, yet the weight or pressure of the air will not explain, nor can be a cause of the coherence of the particles of air themselves. And if the pressure of the aether, or any subtiler matter than the air, may unite, and hold fast together, the parts of a particle of air, as well as other bodies, yet it cannot make bonds for itself, and hold together the parts that make up every the least corpuscle of that materia subtilis.