102 PHILOSOPHICAL THOUGHT. 



eliminate, by numerous repetitions and many co-operators, 

 the subjective errors, the " personal equation " which 

 attaches to every single observation and record. 



Now it will be seen at once that, as all the incidents 

 of mental life are accessible only to one observer, and 

 never repeat themselves even to him, this method of 

 repetition and co-operation, so essential and indispensable 

 in all scientific work, is inapplicable where we have to do 

 with purely introspective or mental phenomena. In fact, 

 the material cannot be prepared and got ready to be 

 handled with the instruments of science in the same way 

 as the material of the scientific worker. In a great many 

 cases also it is only by the fugitive and changing meaning 

 of words that we can transiently fix, to a small extent, 

 the object with which we are dealing. If we try to rid 

 it, as the scientific worker does, of its subjective colour- 

 ing or its personal equation, nothing remains ; whilst 

 attempting to remove the shell we find that we have 

 lost the kernel. 



There is a further point which is almost equally 

 important in dealing with philosophical subjects, and this 

 is that we involuntarily refer every mental, psychical, or 

 introspective phenomenon to a personal unity or whole 

 which we denote by the word mind, soul, consciousness, 

 spirit, or some other similar term, and that we can only 



are recognised to be not infre- 

 quently fallacious. Nowhere is this 

 more the case than in the calculus 

 of probabilities and its applications, 

 a,ri, for instance, in the kinetic 

 theory of gases (see, e.g., 0. E. 

 Meyer, ' Die Kinetische Theorie der 

 Gase,' passim). At one time it was 

 thought that there existed only one 

 type of a fluid ellipsoid in motion, 



till Jacobi discovered another. Also 

 the motion of bodies under the 

 Newtonian law of attraction seemed 

 for a long time confined to conic 

 sections, till G. W. Hill showed the 

 usefulness of dealing with other 

 forms of periodic orbits in the 

 planetary and lunar theories (>ee 

 H. H. Turner, ' Modern Astronomy,' 

 1901, p. 257 sqq.) 



