Relations between the Physical and the Moral. 237 



functions have for their characteristic the fact that they are simul- 

 taneous : digestion, circulation, respiration, the secretions, etc., 

 with all their subdivisions, take place at the same time, and depend 

 on one another. But if we pass from plants to the lower animals, 

 and from them to the higher, we find added to the vital actions 

 other actions which have a tendency to range themselves in simple 

 succession, to be produced under the form of a series. These 

 actions we call psychical. In the radiata, the mollusca, and the 

 articulata, the psychical life has for its centres ganglia dispersed 

 through the animal; the actions of these are .very imperfectly 

 co-ordinated, so that there is rather simultaneousness than succes- 

 sion : hence their mental inferiority. This dispersion of psychical 

 life explains the fact that if we cut in two or more pieces an earth- 

 worm, a centipede, or a praying mantis, each piece of the insect 

 moves and acts on its own account. But in proportion as we 

 ascend in the animal series, the nervous system grows more and 

 more perfect, and the centres are co-ordinated with a view to a 

 higher unity ; simultaneous action gives place to a more and more 

 perfect succession, without however attaining it. This fusion of 

 simultaneousness with succession can never be complete ; and thus 

 the tendency of psychical actions to take the form of a simple 

 series is ever approaching this ideal, but never absolutely attains it. 



We can also attack this problem of the unity of consciousness in 

 another way. We have just seen that it necessarily occurs under 

 the form of a series, a succession that is to say, under condition 

 of time. But time is measurable ; and since to study is to measure, 

 and as accurate science consists of measurement, it follows that 

 consciousness in some degree comes under the cognizance of 

 exact science. 



The experiments made on this subject are of recent date. 

 Towards the close of the last century the Greenwich astronomers 

 remarked that the various observers did not observe in the same 

 way the coming of a star to the meridian. The variations some- 

 times amounted to half a second. Bessel, of Konigsberg, was the 

 first to suppose that this difference was owing to psychological 

 causes, and he set himself to determine this error, or personal equa- 

 tion. From observations made by astronomers, it resulted that 

 some time elapses between the instant when an act is performed 



