Page:Popular Science Monthly Volume 4.djvu/431

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MODERN OPTICS AND PAINTING.
415


which he works, there is obviously implied a power to which he is subject. So that, in Mr. Martineau's doctrine also, there is an Ultimate Unknowable; and it differs from the doctrine he opposes only by intercalating a partially Knowable between this and the wholly Knowable.

Finding, as explained above, that this interpretation is not consistent with itself, and finding, as just shown, that it leaves the essential mystery unsolved, I do not see that it has an advantage over the doctrine of the Unknowable in its unqualified shape. There cannot, I think, be more than temporary rest in a proximate solution which takes for its basis an ultimate insolubility. Just as thought cannot be prevented from passing beyond Appearance, and trying to conceive the Cause behind, so, following out the interpretation Mr. Martineau offers, thought cannot be prevented from asking what Cause it is which restricts the Cause he assigns. And if we must admit that the question under this eventual form cannot be answered, may we not as well confess that the question under its immediate form cannot be answered? Is it not better candidly to acknowledge the incompetence of our intelligence, rather than to persist in calling that an explanation which does but disguise the inexplicable? Whatever answer each may give to this question, he cannot rightly blame those who, finding in themselves an indestructible consciousness of an Ultimate Cause, whence proceed alike what we call the Material Universe and what we call Mind, refrain from affirming any thing respecting it, because they find it as inscrutable in nature as it is inconceivable in extent and duration.

MODERN OPTICS AND PAINTING.[1]

By O. N. ROOD,

PROFESSOR OF PHYSICS IN COLUMBIA COLLEGE.

LECTURE I.

MODERN science has taught us that the portion of the material universe with which we are acquainted is swept from end to end by vibrations, that we are immersed in a sea whose very substance is constantly pulsating under the influence of systems and counter-systems of waves, and that even our very sensations are largely dependent on the action of these undulations upon ourselves. Now, the laws which rule these waves, comparatively speaking, are few and simple; the waves, taken by themselves, are modes of motion which are moderately intelligible; they obey well-known mechanical laws, and can be subjected to ordinary methods of computation. But, when we come to consider their action on living beings, the case is quite

  1. Two lectures delivered before the National Academy of Design.