For the complete understanding of these words, it does not appear that any thing remains to be explained. If one line, proceeding from a central particle, be understood, every line, which can proceed from it, is also understood. If that central point be a part 36 of the human body, it is plain that as the hand, passing along a line in a certain direction from that centre, has certain muscular actions, passing along in another direction, it has muscular actions somewhat different. When we say muscular actions somewhat different, we say muscular feelings somewhat different. Difference of feeling, when important, needs difference of naming.
A particular case of association is here to be remarked; and it is one which it is important for the learner to fix steadfastly in his memory.
We never perceive, what we call an object, except in the synchronous order. Whatever other sensations we receive, the sensations of the synchronous order, are always received along with them. When we perceive a chair, a tree, a man, a house, they are always situated so and so, with respect to other objects. As the sensations of positions are thus always received with the other sensations of an object, the idea of Position is so closely associated with the idea of the object, that it is wholly impossible for us to have the one idea without the other. It is one of the most remarkable cases of indissoluble association; and is that feeling which men describe, when they say that the idea of space forces itself upon their understandings, and is necessary.[11]
[11] Under the head, as before, of Relative Terms, we find here an analysis of the important and intricate complex ideas of Extension and Position. It will be convenient to [defer] any remarks on this analysis, until it can be considered in conjunction with the author’s exposition of the closely allied subjects of Motion and Space.—Ed.
37 2. We come now to the case of naming OBJECTS in pairs, on account of the Successive Order.
We have had occasion to observe that there is nothing in which human beings are so deeply interested, as the Successive Order of objects. It is the successive order upon which all their happiness and misery depends; and the synchronous order is interesting to them, chiefly on account of its connection with the successive.
When we speak of objects, it is necessary to remember, that it is sensations, not ideas, to which we are then directing our attention. All our sensations, we say, are derived from objects; in other words, object is the name we give to the antecedents of our sensations. And, reciprocally, all our knowledge of objects is the sensations themselves. We have the sensations, and that is all. A knowledge, therefore, of the successive order of objects, is a knowledge of the successive order of our sensations; of all the pleasures, and all the pains, and all the feelings intermediate between pleasure and pain, of which the body is susceptible.
Of successions, that is, the order of objects as antecedent and consequent, some are constant, some not constant. Thus, a stone dropped in the air always falls to the ground. This is a case of constancy of sequence. Heavy clouds drop rain, but not always. This is a case of casual sequence.[12] Human life is 38 deeply interested in ascertaining the constant sequences of all the objects from which human sensations are derived. The great business of philosophy is to find them out; and to record them, in the form most convenient for acquiring the knowledge of them, and for applying it.
[12] This is surely an improper use of the word Casual. Sequences cannot be exhaustively divided into invariable and casual, or (as by the author a few pages [further on]) into constant and fortuitous. Heavy clouds, though they do not always drop rain, are not connected with it by mere accident, as the passing of a waggon might be. They are connected with it through causation: they are one of the conditions on which, when united, rain is invariably consequent, though it is not invariably consequent on that single condition. This distinction is essential to any system of Inductive Logic, in which it recurs at every step.—Ed.
In the successions of objects, it very often happens, that what appear to us to be the immediate antecedent and consequent, are not immediately successive, but are separated by several intermediate successions. Thus, the falling of a spark on gunpowder, and the explosion of the gunpowder, appear antecedent and consequent; but several successions in reality intervene; various decompositions, and compositions, in which, indeed, all the sequences cannot as yet be traced. Most of the successions, which we are called upon to notice and to name, are in the same situation. We fix upon two conspicuous points in a chain of successions, and the intermediate ones are either overlooked, or unknown.