INFINITY ETERNITY THE UNTHINKABLE. 191 



has no conceivable limit behind or before us. Eternity, 

 indeed, has become almost exclusively a theological 

 term, to which few can, or dare, attach its full meaning. 

 It is a word of solemn sound, but barren to the under- 

 standing ' a negative idea clothed with a positive 

 name.' 



Numbers, in expressing the quantities and relations 

 of space, motion, and time, as well as the atomic 

 constitution of matter, carry us far into the depths 

 where thought finally loses itself in the infinite. How- 

 ever startling, and to many incredible, the arrays of 

 figures through which science now expounds the great 

 phenomena of nature, these are really the methods 

 which distinguish and protect truth from ignorant and 

 idle speculation. What can be translated into and 

 checked by arithmetic is generally a sound conclu- 

 sion, whatever the amount of numbers concerned. 

 Such figures, indeed, sometimes carry certainty so far 

 beyond the reach of conception that the term Infinite 

 seems justifiably applied to what is in reality but a 

 step towards it. The mathematician, through his 

 peculiar method of interrogating nature, attains some 

 results which no observation or experiment can reach, 

 and often touches on those terminal points where an 

 Infinite in the series stops all progress beyond. Those 

 ultimate ratios, which Berkeley calls 'the ghosts of 

 departed quantities,' approach the depths of the infinite, 

 but halt on the brink. 



The controversies as to motion in the abstract a 

 dispute stretching from the age of Zeno and Aristotle 

 to that of Newton and Boyle and the kindred ques- 



