CHARLES BONNET, an eminent naturalist and philosophical 'writer, was born at Geneva on the 13th March 1720. The Bonnets, a French family whom the religious persecution in the 16th century had driven into Switzerland, were accustomed to fill important posts in the Genevese Government; and young Charles Bonnet was expected to qualify himself to make use of the family influence by becoming a lawyer. But dry legal technicalities proved to be anything but attractive to his rich and imaginative mind, all the more that he found in the study of nature an employment which was not also a task. He made law his profession, but he never seems to have permitted it to interfere seriously with his favourite pursuits. The account of the ant-lion in Pluche's Spectacle de la Nature, which he chanced to read in his sixteenth year, turned his attention in particular to the wonders of insect life. He procured Reaumur's work on insects, and with the help of live specimens succeeded, after minute and patient investigation, in adding many observations to those of Reaumur and Pluche. The result of two years' labour he made known to Reaumur, who was naturally not a little surprised to find so much sagacity and power of research in a youth of eighteen. In 1740 Bonnet communicated to the Academy of Sciences a paper containing a series of experiments establishing what is now termed parthenogenesis in aphides or tree-lice, which obtained for him the honour of being admitted a corresponding member of the academy. In 1741 he instituted a set of experiments respecting the reproduction of worms by fission; and in the following year he discovered that the respiration of caterpillars and butterflies is performed by pores, to which the name of stigmata has since been given. In 1743 he was admitted a fellow of the Royal Society; and in the same year he became a doctor of laws,his last act in connection with a profession which had ever been distasteful to him. His first published work appeared in 1745, entitled Traité d'Insectologie, in which were collected his various discoveries regarding insects, along with a preface on the development of germs and the scale of organized beings. Botany, particularly the leaves of plants, next attracted the attention of Bonnet; and after several years of diligent study, rendered irksome by the increasing weakness of his eyesight, he published, in 1754 one of the most original and interesting of his works, Traité de l'usage des feuilles ; in which among other things he advances many considerations tending to show that plants are endowed with powers of sensation and discernment. But Bonnet's eyesight, which threatened to fail altogether, now caused him to turn his thoughts from investigation to speculation. In 1754 his Essai de Psychologie was published anonymously in London. This was followed in 1760 by the Essai analytique sur les facultes de I'âme, in which he develops his views regarding the physiological conditions of mental activity. He returned to physical science, but to the speculative side of it, in his Considerations sur les corps organisés, Amsterdam, 1762. The principal objects of this work were to give, in. an abridged form, all the most interesting and well-ascertained facts respecting the origin, development, and reproduction of organized bodies, to refute the theory of epigénesis, and to explain and defend the doctrine of pre-existent germs. In his Contemplation de la Nature, which next appeared (1764-5), one of his most popular and delightful works, he sets forth, in eloquent language, the theory that all the beings in nature form a gradual scale rising from lowest to highest, without any break in its continuity. His last important work is entitled Palingénésie Philosophique, (Geneva, 1769) ; in it he treats of the past and future of living beings, and supports the idea of the survival of all animals, and the perfecting of their faculties in a future state. Bonnet's life was singularly uneventful. He seems never to have passed beyond the limits of his native country; nor does he appear to have taken any part in public affairs except for the comparatively short period between 1752 to 1768, during which he was a member of the council of the republic. The last twenty-five years of his life he spent in the country, simple and regular in his mode of life, easy in his circumstances, and happy in a small circle of friends. His wife, whom he married in 1756, was a lady of the family of De la Rive. They had no children, but Madame Bonnet's nephew, the celebrated De Saussure, was brought up as their son. Bonnet died, after a long and painful illness, on the 20th May 1793.
The outlines of Bonnet's philosophical system may be set forth in a few sentences. Man, according to him, is a mixed being, composed of two distinct substances, mind and body,the one immaterial and the other material. In what manner the two are connected we do not know, but of this at least we are certain, that bodily activity is a necessary condition of thought. All knowledge originates in sensations; sensations themselves follow (but whether as physical effects or merely as sequents Bonnet will not say) vibrations in the various nerves appropriate to each; and lastly, the nerves are made to vibrate by the action of outward objects upon them. A nerve once set in motion by a particular object contracts a certain tendency to reproduce that motion ; so that when it a second time receives an impression from the same object it vibrates with less resistance. It is the sensation accompanying this increased flexibility in the nerve that is, according to Bonnet, the condition of memory. When reflectionthat is, the active as distinguished from the merely passive element in mindis applied to the acquisition and combination of sensations, those abstract ideas are formed which are usually placed in opposition to sensations, but which are thus, no matter how refined they may appear, sensations in combina-tion only. That which puts the mind into activity is pleasure or pain; happiness is the end of human existence. Bonnet's metaphysical theory is based on two principles borrowed from Leibnitz,first, that there are not successive acts of creation, but that the universe is completed by the original act of the divine will, and thereafter moves on by its own inherent force; and, secondly, that there is no gap in the continuity of existence. The divine Being, according to Bonnet, origi-nally created a multitude of germs in a graduated scale, each with an inherent power of self-development. At every successive step in the progress of the globe, these germs, or what has been developed in their place, advance nearer to perfection; if some advanced and others did not there would be a gap in the continuity of the chain. Thus not man only but all other forms of existence are immortal. Nor is it man's mind merely; his body also will pass into the higher stage, not, indeed, the body he now possesses, but a finer one of which the germ at present exists within him. This is equally true of the other animals, who also possess a germ that will develop itself in the next stage; and every individual begins each successive stage with that amount of perfection and of knowledge which he had when he left the previous stage. It is impossible, however, to reach absolute perfection, because the distance is infinite. It is difficult to reconcile this last proposition with the law of continuity, if that law is to be accepted, as Bonnet seems to accept it, as an absolute principle of the universe, embracing all exist-ence divine and created, for surely the interval between the divine Being and the highest created being, constantly lessening though it be, is a break in the continuity of the chain. It is also difficult to understand whether the con-stant advance to perfection is performed by every individual on his own account, or only by each race of beings as a whole. Is a man when he dies at once translated to the next stage, or must he wait until the time comes when the advancement of the whole human race takes place, before he, at any rate consciously, realizes the new state 1 There seem, in fact, to be two distinct but somewhat analogous doctrines,that of the constantly increasing advancement of the individual in future stages of existence, and that of the constantly increasing advancement of the race as a whole according to the successive evolutions of the globe.
Bonnet's complete works appeared at Neufchatel in 1779-1785, partly revised by himself. An English translation of certain portions of the Palingenesie Philosophique was published in 1787, under the title, Philosophical and Critical Inquiries concerning Christianity. (See A. Lemoine, Charles Bonnet, Paris, 1850; and the Duc de Caraman's Charles Bonnet, philosophe et naturaliste, Paris, 1859.)