Essays Towards a Theory of Knowledge | Page 3

invention, cr��ation de formes, elaboration continue de l'absolument nouveau."
[14:1] Recently, we believe, astronomers have favoured the view that the day of Venus is equal in length to her year.

II
THE ORIGIN OF PHYSICAL CONCEPTS
"Penser c'est sentir," said Condillac. "It is evident," said Bishop Berkeley, "to one who takes a survey of the objects of Human Knowledge that they are either ideas actually imprinted on the senses or else such as are perceived by attending to the passions and operations of the Mind, or lastly ideas formed by help of memory and imagination either combining, dividing, or barely representing those originally perceived in the foresaid ways." J. S. Mill tells us, "The points, lines, circles, and squares which one has in his mind are, I apprehend, simply copies of points, lines, circles, and squares which he has known in his experience," and again, "The character of necessity ascribed to the truths of Mathematics and even, with some reservations to be hereafter made, the peculiar certainty attributed to them is an illusion." "In the case of the definitions of Geometry there exist no real things exactly conformable to the definitions." Again Taine, "Les images sont les exactes reproductions de la sensation." Again Diderot, "Pour imaginer il faut colorer un fond et d��tacher de ce fait des points en leur supposant une couleur differente de celle du fond. Restituez �� ces points la m��me couleur qu'au fond,--�� l'instant ils se confondent avec lui et la figure disparait," etc. Again, Dr. Ernest Mach, Vienna, remarks, "We are aware of but one species of elements of Consciousness: sensations." "In our perceptions of Space we are dependent on sensations." Dr. Mach repeatedly refers to "space-sensations," and indeed affirms that all sensation is spatial in character.[18:1]
According to the view of Knowledge of which we have extracted examples above, the ideas of the mind are originally furnished to it by sensation, from which therefore are derived, not necessarily all our Thoughts, but all the materials of Discourse, all that constitutes the essence of Knowledge.
Our purpose at the moment is to show that this view is altogether false, and our counter proposition is, that it is from our Activity that we derive our fundamental conceptions of the external world; that sensations only mark the interruptions in the dynamic Activity in which we as potent beings partake, and that they serve therefore to denote and distinguish our Experience, but do not constitute its essence.
We do not propose now to devote any time to the work of showing that sensations from their very nature could never become the instruments of Knowledge. We propose rather to turn to the principal ideas of the external world which are the common equipment of the Mind in order to ascertain whether in point of fact they are derived from Sensation.
Of course to some extent the answer depends on what we mean by Sensation. If by that term we intend our whole Experience of the external, then of course it necessarily follows--or, at least, we admit--that our Knowledge of the external must be thence derived. But such a use of the term is loose, misleading, and infrequent. The only safe course is to confine the term Sensation to the immediate data of the five senses--touch, sight, hearing, smell, and taste, with probably the addition of muscular and other internal feelings. It is in this sense that the word is usually employed, and has been employed by the Sensationalist School themselves.
Now we might perhaps begin by taking the idea of Time as a concept constantly employed in Discourse, but of which it would be absurd to suggest that it is supplied to us by Sensation. It might, however, be urged in reply that the idea of Time is not derived from the external world at all, but is furnished to us directly by the operations of the Mind, and that therefore its intellectual origin need not involve any exception to the general rule that the materials of our Knowledge of the world are furnished by Sensation alone. Without, therefore, entering upon any discussion of the interesting question as to what is the real nature of Time, we shall pass to the idea of Space.
Mach, the writer whom we have already quoted, in his essay on Space and Geometry speaks constantly and freely of sensations of Space, and as there can be no denial of the fact that Space is a constituent of the external world, it would seem to follow that those who hold Sensation to be the only source of our Knowledge must be obliged to affirm the possibility of sensations of Space. Mach indeed claims to distinguish physiological Space, geometrical Space, visual Space, tactual Space as all different and yet apparently harmoniously blended in our Experience. He is, however, sadly wanting in clearness of statement. He