MODERN OPTICS AND PAINTING. 415 



which he works, there is obviously implied a power to which he is sub- 

 ject. 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 con- 

 sistent 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 incompe- 

 tence of our intelligence, rather than to persist in calling that an expla- 

 nation 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 0. N. KOOD, 



PROFESSOR Off PHYSIOS IX COLUMBIA COLLEGE. 



LECTUKE 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 de- 

 pendent 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. Rut, when 

 we come to consider their action on living beings, the case is quite 

 1 Two lectures delivered before the National Academy of Design. 



