From Étienne Geoffroy Saint-Hilaire, "Sur une vue scientifique de l'adolescence de Napoléon Bonaparte, formulée dans son age mûr sous le nom de 'Monde des détails'," Paris: De Brun, 1835.
... at the age of fifteen years, Napoleon saw as possible means only two viable routes: one must choose between arms and the sciences. I heard him explain it as follows: "Taking up arms has become my profession, and was not my choice, and I found myself so engaged as a result of circumstances."
Indeed, it was in the final hours of our stay in Cairo, and in the forced and prolonged leisure of awaiting the final preparations for the voyage to France, that the general in chief of the Oriental Army made these curious revelations... "When I was young," Napoleon said, "I got it into my mind to become a discoverer, a Newton."
The scene repeated itself in the gardens of the Esbekieh palace, in the company of elite men, the principal officers of the army. Monge, an interlocutor [of Napoleon] given first priority, discussed the matter in question: it was perhaps for the first time in the campaign that he did not share the opinion of the general. Monge stressed the significance of that beautiful saying of Lagrange: "No one will attain the glory of Newton, there was only one world to discover."
But the general in chief, with what a lively and heated tone did he reply! It was evidently a thought that he had long held back that now escaped. "What have I heard here? But what of the World of Details! Who has ever dreamed of this other world? Since the age of fifteen years I have believed in it... and this memory lives in me like an idée fixe never to be abandoned."
[Geoffroy adds in a footnote: "the expression 'phenomenal world' would, I believe, have better captured the meaning of the scientific and philosophical ideas of the illustrious thinker."]
What the astronomical world had of importance was not lacking in his World of Details. The immensity of things, like the perfection of their arrangement, was seen to be acquired in the consideration of the smallest atoms cast off from the stellar worlds, by the production of the luminous fluid that these great bodies sent to the earth. And it was also of the same grandeur, for is it not in the depth of those details proper to our planetary body that the human species finds itself living there and finds its needs taken care of? Is it not by the concourse of these infinite Proteuses that the imposing masse of the earth's animated crust is organized? What is this, if not the immense laboratory in which we have been placed, one of the regions of the World of Details, of the phenomenal world?
Napoleon did not allow his courageous interlocutor to rest for a moment. He continued his reflections: "I ask you, Monge, who has paid attention to the tension and the traction of these tiny atoms at a very short distance, of which we are in a certain sense the obligated observers? I ask you, Monge, would this have been discovered? Would you, Monge, or your Newton, have discovered it?
"See, now: would not this be more beautiful, greater, but above all more profitable to society than philosophical speculation? Newton seems to have solved the problem of movement in general through his discovery of the planetary system. It's beautiful for you men of the mind and of mathematics. But that I should have come to teach men how the movement arises that communicates and is determined by the intervention of the smallest bodies, I would have solved the problem of the life of the universe. And had I done this, which I take to be a real possibility, I would have surpassed Newton by all the distance that exists between matter and intelligence. There is thus nothing exact in your saying from Lagrange, since the World of Details remains to be explored. This is the other world, and it is the most important of all, which I flatter myself with having discovered. Thinking about it, I am still filled with regrets. Thinking about it, I feel pain in my soul."
I sought to penetrate thoroughly into the meaning of these sentences, and I believed I understood by them that he had, confusedly no doubt, come upon the idea of the conditions of essence and of elective affinity, which characterize every sort of atomic material. This thought leading the mind to the notion of a first principle of things, leads us to the sentiment of a nature at war with itself, effecting the separation of materials that are of a contrary essence, or bringing together elements of the same origin, which it assembles with predilection, which it coordinates with harmony, and from which, finally, it forms these marvelous aggregates, its most admirable machines, the organized living beings: composites in which the proper agreement of constitutive elements engenders the capacities and freedoms of a thousand partial and concurrent actions.
I thought from then on that I had rediscovered at the core of this profound idea [of the World of Details] the ingenious idea that we find in Kepler: namely, that the cause that places, Deo juvante, the order and harmony of nature under the spring and the omnipotence of a single lever, is to be determined and is determinable: this idea of a first principle of things, I have done nothing other than to translate it in my opinions recently elucidated when I gave the formula of my universal law, which I have developed and which has become my principle of the attraction of like by like.
In another work, the Études progressives d'un naturaliste pendant les années 1834 et 1835 (Paris: Roret, 1835), Geoffroy explicitly identifies his principle of elective affinity, or the principle of attraction of like to like, as Leibnizian in origin:
Crocodilians definitely show very well that they are a perfectly harmonious assemblage of simple materials, fixed in their essence and originally endowed with their reason of affinities (like attracting like); whence the uniformity prescribed to nature. Nonetheless each of these simple materials is called to its share of eventuality, when there arises a combination by the grouping together of diverse corpuscles. These are then as much arrangements of a second order that concern the respective position, the effects of proportion, the number and forms of component elements. And here is the unique source where Nature deploys all of its power, all the luxuriance of its magnificence, in nuancing each thing, in planting the seeds of the charm of variety, and in so doing deriving infinite pleasure. Thus we are constantly led back to the great idea of the luminous and eminently philosophical a priori of Leibniz: all order of the universe is accomplished by the simultaneity of action of two contrary essences, unity and variety: principles that are in perpetual battle, the cause of the animation of all that exists, the incomprehensible dualism, under the empire of which matter is thrown about and will remain agitated without end.