MEASUREMENTS I43 



though interesting would certainly be vain, but will restrict 

 myself to reminding the reader that, in respect to ourselves, 

 to the ephemeral duration of our existence, the difference 

 between the rates of evolution, admitting that this difference 

 exists, would by its colossal size in itself suffice to introduce 

 fundamental differences in the phenomena observed. Indeed, 

 it is known that a great number of the physical properties of 

 matter are determined by the speed of the objects. For 

 instance, by the velocity of the electrons or of the molecules. 

 Mass itself, a basic quality of matter, is a function of velocity. 

 If electrons, or any other projectile, could attain the velocity 

 of light, their mass would become infinite. These are not 

 simple views of the mind, but result from experiments made, 

 amongst others, by Kaufman in 1901 and by Bucherer more 

 than twenty years ago, in which they studied quantitatively 

 the variations of the mass of the electron as a function of its 

 velocity. At our scale, it is a well-known fact that there is 

 a big difference if wc are hit by a bullet having a velocity of 

 one metre per second or by one travelling at six hundred 

 metres a second. A spout of water a few centimetres in 

 diameter falling from the height of the Eiffel Tower has the 

 rigidity of an iron bar and cannot be cut by the stroke of 

 a sword. 



We are therefore authorized to think that, from the point 

 of view of our senses and of our consciousness, things can be 

 different according to whether the cycle of existence is longer 

 or shorter and according to whether the rhythm of the reactions 

 is more or less accelerated. For a given species, the persistence 

 of life is a discontinuous phenomenon. The individual, like 

 a rocket tracing its luminous trajectory in space, gives birth 

 to another individual, just as if the rocket on coming back to 

 earth put fire to another rocket and so on.^ This sequence of 



^ 'Life appears like a current which goes from germ to germ by 

 the intermediary of a developed organism' (Bergson). We do not 

 know, but it is perhaps the current alone which counts in the history 

 of the universe. For man, on the contrary, it is the intermediary 

 which counts, and the integral phenomenon of which he is only an 

 element escapes him. 



