16. Though we say that plants and animals are formed of the same constituents as minerals, it is necessary to understand this statement in a purely material sense, as it has reference only to the body.
Without speaking of the intelligent principle, which is a question by itself, there is in organic matter a special indiscernible principle, which has never yet been defined: it is the vital principle. This principle, which is active in living beings, though extinct in beings deprived of life by death, nevertheless gives to them characteristic properties, distinguishing them from inorganic substances. Chemistry, which decomposes and recomposes the greater part of inorganic bodies, has power to decompose organic bodies, but has never known to reconstruct even a dead leaf, which is a conclusive proof that there is something in one which does not exist in the other.
17. Is the vital principle something distinct, having a separate existence before it enters the systematic unity of the generative element? Or is it only a particular state, one of the modifications of the universal cosmic fluid, which has become the principle of life, as light, fire, heat, electricity? It is in this last sense that the question is solved by the communications connected with this subject (chap. VI, “General Uranography”).
But, whatever the opinion be concerning the nature of the vital principle, we know it exists as we see the effects of it. One can then admit logically that, in forming themselves from it, organic beings have assimilated the vital principle necessary to their existence as immortal beings; or, if one wishes to say that this principle has been developed in each individual through a combination of elements under the rule of certain circumstances, one sees heat, light, and electricity develop themselves.
18. Oxygen, hydrogen, nitrogen, and carbon, in combining themselves without the vital principle, form only a mineral or inorganic body. The vital principle, modifying the molecular constitution of this body, gives to it special properties. In place of a mineral molecule is found a molecule of organic matter.
The activity of the vital principle is sustained during life by the action of the organs, as is heat by the rotary movement of a wheel. As this action ceases with death, the vital principle is extinguished, as heat is when the wheel ceases to turn. But the effect produced upon the molecular state of the body by the vital principle lives after its extinction, just as the carbonization of wood continues after the extinction of heat. In the analysis of organic bodies, chemistry finds again the constituent elements, oxygen, hydrogen, nitrogen, and carbon; but it cannot reconstruct them, because the cause exists no more: and thus the effect cannot be reproduced, although it can reconstruct a stone.
19. We have taken as an illustration heat generated by the movement of a wheel, because it is a common effect known to all and easier to comprehend; but it had been more exact to say, that in the combination of elements needed to form organic bodies, they are developed by electricity. Organic bodies are therefore veritable electric batteries which operate to the extent that the elements composing them are in a condition to generate electricity, which is life. When these conditions are arrested, death ensues. The vital principle can be none other than a particular kind of electricity designated under the name of animal electricity, evolved during life by the action of the organs, of which the production is arrested by death owing to the cessation of this action.