Radiant Forces, 143 



at the conception of a mental and moral cause adequate 

 to the production of the effects which we observe. A philo- 

 sophy of science which can rest satisfied that man's most 

 heroic purpose and action is nothing more than an oxydation 

 of particles, can only satisfy a few abnormal minds. Such 

 may be wanted to assist in the process of rigid analysis and 

 investigation, to which they often supply a valuable negative 

 stimulant ; but from the earliest times in which speculation 

 existed, down to our own, an overwhelming majority of the 

 greatest intellects Lave taken another view; and while some 

 have regarded physical forces as merely the exponents of 

 moral and intelligent forces, all have seen in secondary causes 

 the proofs of an ultimate cause; and have regarded the universe 

 not as dead and material, but as spiritual, living and divine. 



The present paper is put forward tentatively, with a view 

 to promote thinking on the subjects to which it alludes. Text 

 books and teachers too often leave students with technical 

 statements, which, although correct, supply only an appear- 

 ance of knowledge to those who accept them without careful 

 examination. The intricate nature of optical questions, neces- 

 sitates considerable mathematical knowledge for their com- 

 plete exhaustion, but the questions started in this paper ought 

 to be susceptible of elucidation, so far as main principles 

 extend, in the language of common life. 



Our line of examination seems to show, that if light 

 is presumed to propagate its undulations in concentric 

 spherical waves, it is inexpedient, as well as incorrect, to 

 speak of diverging and parallel rays. What are called 

 diverging rays would be the supposed radii of the circle 

 or sphere formed by each wave. Parallel rays would be 

 merely a portion of a spherical wave having a large diameter 

 and a low rate of curvature for any small portion of it ; while 

 diverging rays would really be a portion of a smaller sphere 

 with a greater curvature of a given portion. A part of the 

 circumference of a sufficiently large circle is approximately a 

 straight line. 



