SUMMARY. 89 



and above the accumulation of facts), the theory of evo- 

 lution, the antiquity of man, and the far greater antiquity 

 of the world itself ; the correlation of physical forces 

 and the conservation of energy ; spectrum analysis and 

 its application to celestial physics ; the higher algebra 

 and the modern geometry ; lastly, the innumerable ap- 

 plications of science to practical life as, for instance, in 

 photography, the locomotive engine, the electric tele- 

 graph, the spectroscope, and most recently the electric 

 light and the telephone. 



To Science, again, we owe the idea of progress. 

 The ancients, says Bagehot, ' had no conception of pro- 

 gress ; they did not so much as reject the idea ; they 

 did not even entertain it.' It is not, I think, going too 

 far to say that the true test of the civilisation of a nation 

 must now be measured by its progress in science. It is 

 often said, however, that, great arid unexpected as the 

 recent discoveries have been, there are certain ultimate 

 problems which must ever remain unsolved. For my 

 part, I would prefer to abstain from laying down any 

 such limitations. When Park asked the Arabs what 

 became of the sun at night, and whether the sun was 

 always the same, or new each day, they replied that 

 such a question was childish, and entirely beyond the 

 reach of human investigation. I have already mentioned 

 that, even as lately as 1842, so high an authority as 

 Comte treated as obviously impossible and hopeless any 

 attempt to determine the chemical composition of the 

 heavenly bodies. Doubtless there are questions the 

 solution of which we do not as yet see our way even to 

 attempt ; nevertheless the experience of the past warns 

 us not to limit the possibilities of the future. 



