﻿THE 
  UNFATHOMED 
  UNIVERSE 
  11 
  

  

  gravitation 
  holds 
  absolutely, 
  and 
  states 
  without 
  hypothesis 
  

   how 
  the 
  motions 
  of 
  the 
  bodies 
  and 
  the 
  earth 
  are 
  mutually 
  

   affected. 
  But 
  if 
  we 
  proceed, 
  with 
  Le 
  Sage 
  or 
  some 
  other, 
  

   to 
  a 
  theory 
  of 
  gravitation, 
  we 
  enter 
  a 
  realm 
  of 
  imaginative 
  

   construction. 
  We 
  work 
  with 
  concepts 
  which 
  are, 
  no 
  doubt, 
  

   ingenious, 
  well-thought-out, 
  consistent, 
  and 
  useful; 
  but 
  how 
  

   far 
  they 
  correspond 
  to, 
  or 
  are 
  representative 
  of 
  objective 
  

   entities 
  is 
  a 
  question 
  to 
  be 
  carefully 
  considered. 
  Sometimes 
  

   the 
  concepts 
  that 
  are 
  effectively 
  worked 
  with 
  are 
  obviously 
  

   mere 
  symbols; 
  thus 
  no 
  one 
  supposes 
  that 
  carbon 
  atoms 
  are 
  

   really 
  like 
  their 
  quite 
  useful 
  quadrumanous 
  diagrammatic 
  

   representations 
  in 
  books 
  on 
  chemistry. 
  The 
  difficulty 
  is 
  in 
  

   regard 
  to 
  subtler 
  symbols 
  or 
  concepts, 
  which 
  work 
  so 
  well 
  

   that 
  we 
  inevitably 
  come 
  to 
  think 
  of 
  them 
  as 
  objective 
  actual- 
  

   ities. 
  And 
  it 
  may 
  be 
  that 
  what 
  was 
  at 
  first 
  an 
  imaginative 
  

   thought-economising 
  symbol, 
  part 
  of 
  a 
  system 
  of 
  intellectual 
  

   shorthand, 
  will 
  be 
  actually 
  verified 
  in 
  Nature. 
  Thus 
  many 
  

   physicists 
  now 
  speak 
  confidently 
  and 
  convincingly 
  of 
  the 
  

   ' 
  reality 
  ' 
  of 
  the 
  atom. 
  When 
  it 
  is 
  legitimate 
  to 
  speak 
  of 
  

   a 
  scientific 
  symbol 
  as 
  real 
  is 
  a 
  matter 
  for 
  the 
  experts 
  only, 
  

   as 
  is 
  plain 
  enough 
  from 
  their 
  disagreement. 
  Thus 
  the 
  ether 
  

   was 
  declared 
  by 
  Lord 
  Kelvin 
  to 
  be 
  the 
  greatest 
  certainty 
  in 
  

   physics, 
  while 
  we 
  find 
  the 
  upholders 
  of 
  the 
  Principle 
  of 
  

   Relativity 
  declaring 
  that 
  the 
  Victorian 
  ether 
  and 
  the 
  Vic- 
  

   torian 
  matter 
  must 
  both 
  go. 
  Similarly 
  in 
  biological 
  prob- 
  

   lems, 
  such 
  as 
  those 
  centred 
  in 
  inheritance, 
  there 
  is 
  diver- 
  

   gence 
  of 
  opinion 
  as 
  to 
  the 
  objectivity 
  of 
  t 
  biophores 
  ', 
  

   6 
  determinants 
  ', 
  ' 
  factors 
  ', 
  and 
  i 
  genes 
  ', 
  though 
  these 
  are 
  

   very 
  useful 
  in 
  formulating 
  conclusions 
  and 
  prompting 
  fur- 
  

   ther 
  questions. 
  

  

  (c) 
  Third, 
  it 
  has 
  to 
  be 
  remembered 
  that 
  the 
  descriptive 
  

   formulae 
  are 
  more 
  than 
  summations 
  of 
  the 
  routine 
  of 
  in- 
  

  

  