Page:Mind (Old Series) Volume 11.djvu/465

464 A. BAIN : less exercising some power. To a being with only one sense, the experience of sensations of that sense would not be exactly the same as to us, who bring five senses into omparison. On the whole, I am quite disposed to acquiesce in Mr. Ward's conclusion, that while there is no unalterably fixed unit in sensations, the mutual relations of impressions are not everything. I am concerned only to uphold certain positions that constantly meet us in practice, as well as in theory. Thus, (1) change of impression is essential to consciousness of any kind, and the intensity of the con- sciousness is determined by the amount or interval of the change, a matter of the greatest moment in the question as to conscious intensity, for which the comprehensive title is now to be Attention. (2) We cannot assign the conscious- ness due to any present stimulus without taking account of the state of mind previous, innumerable fallacies of judgment being the consequence of overlooking this principle. Among important applications of the general law is this : a term or quality has no meaning till we have experienced some oppo- site to it, if only a change in degree. Our first parents did not at first know the meaning of obedience. The Austra- lians, who never had a stimulant until the British occupation of their territory, did not know that they were temperate ; those that now take the pledge understand it. Under the head " Sensation and Movement " there is first the inquiry as to whether qualitative difference in sensation is not resolvable into variety in the arrangement and intensity of the aggregation of primitive homogeneous units. There is much to be said for this as an interesting specula- tion. Another point urged is that all possible sensations of colour, tone, temperature constitute groups of qualitative continua. This applies to cases where the changes are made by imperceptible gradations ; while the transitions that are in their nature abrupt, as the change from a smell to a taste, or from sweet to bitter, constitute a distinct class. The hypothetical explanation of the last is a higher degree of complexity. As regards movements and motor presentations, the want of qualitative difference is notable. Mr. Ward divides them into two classes motor presentations proper, involving feeling of muscular effort, and auxilio-motor, due to the straining of tendons, stretching of the skin, &c. He says nothing of the sensibility due to the afferent nerve-fibres in muscle, which are not there for nothing. Nor does he either affirm or deny the position that the motor currents are