Page:Mind (New Series) Volume 9.djvu/491

 THE PRINCIPLE OF I, KAST ACTION, ETC. 177 least action from the principle of virtual velocities, in fact all mechanical principles can be deduced indifferently one fn.m the other, all being mere varying forms for expressing some one fundamental physical fact. No one of them can there- fore be said to be more ultimate than the rest, except from the point of view of convenience, i.e., of theoretical simplicity, that principle being the most ultimate from this point of view which entails the simplest deductive superstructure and has the simplest real import. But here we must distinguish. Mental process is not a fact of the same order as mechanical work. 1 The unity and continuity of mental process are facts which derive their richest meaning from considerations totally inapplicable to mechanical work. Mental process is a vital, rational process, a conscious striving. 2 The unity of mental process, its fundamental fact, involves, therefore, not merely a certain abstract continuity such as is given in the unity of a move- ment in space from one point to another, but a continuity proper to a something that grows, and grows by thinking. The Unity of Consciousness is abstractly one simply in so far as it is continuous or persistent. It is a vital unity from the beginning in virtue of the fact that whatever meaning or skill is acquired is, from the moment we begin to learn by experience, i.e., to develop, utilised for the further acquisi- tion of meaning or skill. It is a vital unity in virtue of the cumulative nature of its activity. It is a rational unity, at the outset, only in the sense that its vital unity is not mere unity or continuity of life as in the case of a plant or diatom, but unity and continuity of interest and attention. In all that follows we shall understand by the vital Unity of Con- sciousness that primary unity which is not only the basis of growth generally, but of that specific form of growth which is known as mental development. We presuppose the rational activities whereby unity of experience is acquired. By the cumulative activity of Consciousness, as displayed in 1 And yet Mach's fundamental principle of mechanics, that work is the factor determinative of motion and that where there is no longer any work to be done, there can no longer be any motion, is interestingly like an abstract statement of the fundamental principles of psychical activiu which connects effort with the impulse to satisfy felt needs, stating that effort variously adapts itself so long as the impulse still remains unsatisfied, but ceases to be, so soon as the impulse is satisfied. 2 Or, as we might have put it, though less aptly for the purpose we have in view, mental process is a process made up of impulses and their controlling, and mental development, the gradual acquisition of a more determinate and organised control over impulse. ('/. Lloyd Morgan's Comparative Psychology, p. 182.