Every one has met with books which, according to his turn of mind, have been epoch-making, opening to him horizons whose very existence he had never guessed. They throw wide open the gates of a new world where henceforward he will use his mental powers; they are the spark which, falling on a hearth, kindles into flame materials otherwise never utilised. And very often it is mere chance which puts into our hands some book which makes a new starting-point in the evolution of our ideas. The most casual circumstance, a few lines which happen to come under our eye, decide our future and impel us into the path which thenceforward we shall follow. One winter evening, beside a stove where the ashes were yet warm, while my family slept, I was forgetting, while I read, all the cares of the morrow—the black cares of the professor of physics, who, after having piled one university diploma on another and rendered for a quarter of a century services whose merit was not denied, earns for himself and family 1600 francs—less than a groom in a well-to-do household. Such was the shameful parsimony of that day in educational matters; thus did Red tape will it. I was a free-lance, son of my solitary studies. Thus, amid my books I was putting aside acute professorial worries when I chanced to light on an entomological pamphlet which had come into my hands I forget how. It was by the patriarch of entomology of that day, the venerable savant Léon Dufour, on the habits of a Hymenopteron whose prey was the Buprestis. Certainly long ere this I had felt a great interest in insects; from childhood I had delighted in beetles, bees, and butterflies; as far back as I can recollect I see myself enraptured by the splendours of a beetle’s elytra, or the wings of the great Swallowtail butterfly. The materials lay ready on the hearth, but the spark to kindle them had been lacking. The accidental perusal of Léon Dufour’s pamphlet was that spark. I had a mental revelation. So then to arrange lovely beetles in a cork box, to name and classify was not the whole of science; there was something far superior, namely, the close study of the structure, and still more of the faculties of insects. Thrilled by emotion I read of a grand instance of this. A little later, aided by those fortunate circumstances which always befriend the ardent seeker, I published my first entomological work, the complement of Léon Dufour’s. It gained the honours of the Institute of France, a prize for experimental physiology being adjudged to it, and—far sweeter reward!—shortly after I received a most flattering and encouraging letter from the very man who had inspired me. From far away in the Landes the venerated master sent me the cordial expression of his enthusiasm, and urged me to continue my studies. At that recollection my old eyes still grow wet with a holy emotion. Oh, bright days of illusion, of faith in the future, what has become of you!