THE SKY 141 



through the limitations of the senses, and to seek beyond 

 them the roots and reasons of the phenomena which the 

 observer and experimenter record. To such spirits ad- 

 venturous and firm we are indebted for our deeper knowl- 

 edge of the methods by which the physical universe is 

 ordered and ruled. 



In his efforts to cross the common bourne of the known 

 and the unknown, the effective force of the man of science 

 must depend, to a great extent, upon his acquired knowl- 

 edge. But knowledge alone will not do ; a stored memory 

 will not suffice; inspiration must lend its aid. Scientific 

 inspiration, however, is usually, if not always, the fruit 

 of long reflection of patiently ' 'intending the mind," as 

 Newton phrased it; and as Copernicus, Newton, and Dar- 

 win practiced it; until outer darkness yields a glimmer, 

 which in due time opens out into perfect intellectual day. 

 From some of his expressions it might be inferred that 

 Newton scorned hypotheses; but he allowed them, never- 

 theless, an open avenue to his own mind. He propounded 

 the famous corpuscular theory of light, illustrating it and 

 defending it with a skill, power, and fascination which 

 subsequently won for it ardent supporters among the best 

 intellects of the world. This theory, moreover, was 

 weighted with a supplementary hypothesis, which as- 

 cribed to the luminiferous molecules "fits of easy refleo* 

 tion and transmission," in virtue of which they were some- 

 times repelled from the surfaces of bodies and sometimes 

 permitted to pass through. Newton may have scorned the 

 levity with which hypotheses are sometimes framed; but 

 he lived in an atmosphere of theory, which he, like all 

 profound scientific thinkers, found to be the very breath 

 of his intellectual life. 



