30 PASTEUR: THE HISTORY OF A MIND 



there today, as well as from the other tartaric acid 

 factories. 



What is the mechanism of this production of a right- 

 handed substance without a trace of the left-handed one, 

 or inversely? Are the two forms produced simultan- 

 eously and is one of them utilized and consumed in 

 proportion to its production? In this case nature would 

 behave like a chemist who, after having formed at the 

 same time the two inverse substances, should separate 

 them and cast aside one of them in order to preserve the 

 other. Some facts which we shall soon encounter are in 

 accord with this view. Pasteur adopted another view 

 which, however, is not exclusive of the first. Possessed 

 as he was by this novel idea of dissymmetry, he boldly 

 connected the dissymmetry of natural products with the 

 dissymmetry of their source. The earth is round, it is 

 true, but, he thought, it is only when in a state of repose 

 that it is symmetrical and superposable on itself. As 

 soon as it turns on its axis its image in a glass no longer 

 resembles it, for that turns in a different direction. The 

 sun's rays, which strike and animate a leaf of a plant, 

 no longer have the same direction in the earth and in its 

 image. If there is an electric current circulating in the 

 direction of the equator and presiding over the distribu- 

 tion of magnetism, this current turns also in opposite 

 directions in the earth and its image in the mirror. In 

 short, the earth is a dissymmetrical whole from the point 

 of view of the forces which make it live, it and all that it 

 produces, and it is on this account that, as soon as they 

 have exceeded a certain degree of complexity, the sub- 

 stances which the earth's living creatures produce are 

 dissymmetrical and endowed with a rotary power. 



With this idea in mind, Pasteur had tried to crystallize 

 the tartrates in the presence of dissymmetrical forces, 

 for example, the poles of a magnet, and to make a plant 



