Quick Volition springs, l. 73. Volition is an exertion or change of the central parts of the sensorium, or of the whole of it terminating in some of those extreme parts of it which reside in the muscles and organs of sense. The vulgar use of the word memory is too unlimited for our purpose: those ideas which we voluntarily recall are here termed ideas of recollection, as when we will to repeat the alphabet backwards. And those ideas which are suggested to us by preceding ideas are here termed ideas of suggestion, as whilst we repeat the alphabet in the usual order; when by habits previously acquired B is suggested by A, and C by B, without any effort of deliberation. Reasoning is that operation of the sensorium by which we excite two or many tribes of ideas, and then reexcite the ideas in which they differ or correspond. If we determine this difference, it is called judgment; if we in vain endeavour to determine it, it is called doubting.
If we reexcite the ideas in which they differ, it is called distinguishing. If we reexcite those in which they correspond, it is called comparing.[Back to Canto]
Each passing moment, l. 81. During our waking hours, we perpetually compare the passing trains of our ideas with the known system of nature, and reject those which are incongruous with it; this is explained in Zoonomia, Sect. XVII. 3. 7. and is there termed Intuitive Analogy. When we sleep, the faculty of volition ceases to act, and in consequence the uncompared trains of ideas become incongruous and form the farrago of our dreams; in which we never experience any surprise, or sense of novelty.[Back to Canto]
Association steers, l. 91. Association is an exertion or change of some extreme part of the sensorium residing in the muscles and organs of sense in consequence of some antecedent or attendant fibrous contractions. Associate ideas, therefore, are those which are preceded by other ideas or muscular motions, without the intervention of irritation, sensation, or volition between them; these are also termed ideas of suggestion.[Back to Canto]
The branching forehead, l. 103. The peculiarities of the shapes of animals which distinguish them from each other, are enumerated in Zoonomia, Sect. XXXIX. 4. 8. on Generation, and are believed to have been gradually formed from similar living fibres, and are varied by reproduction. Many of these parts of animals are there shown to have arisen from their three great desires of lust, hunger, and security.[Back to Canto]
The tropic eel, l. 111. Gymnotus electricus.[Back to Canto]
The fly of night, l. 113. Lampyris noctiluca. Fire-fly.[Back to Canto]
The hand, first gift of Heaven, l. 122. The human species in some of their sensations are much inferior to animals, yet the accuracy of the sense of touch, which they possess in so eminent a degree, gives them a great superiority of understanding; as is well observed by the ingenious Mr. Buffon. The extremities of other animals terminate in horns, and hoofs, and claws, very unfit for the sensation of touch; whilst the human hand is finely adapted to encompass its object with this organ of sense. Those animals who have clavicles or collar-bones, and thence use their forefeet like hands, as cats, squirrels, monkeys, are more ingenious than other quadrupeds, except the elephant, who has a fine sense at the extremity of his proboscis; and many insects from the possessing finer organs of touch have greater ingenuity, as spiders, bees, wasps.[Back to Canto]
Trace the nice lines of form, l. 125. When the idea of solidity is excited a part of the extensive organ of touch is compressed by some external body, and this part of the sensorium so compressed exactly resembles in figure the figure of the body that compressed it. Hence when we acquire the idea of solidity, we acquire at the same time the idea of figure; and this idea of figure, or motion of a part of the organ of touch, exactly resembles in its figure the figure of the body that occasions it; and thus exactly acquaints us with this property of the external world.
Now, as the whole universe with all its parts possesses a certain form or figure, if any part of it moves, that form or figure of the whole is varied. Hence, as motion is no other than a perpetual variation of figure, our idea of motion is also a real resemblance of the motion that produced it.