Scarcely two years later Mill died suddenly at Avignon. Grief finally killed him; for this unexpected death seemed to have been only the ultimate climax of the secret malady which had so long been undermining him. It was in the outskirts of Orange that Fabre for the last time met him and accompanied him upon a botanizing expedition. He was struck by his weakness and his rapid decline. Mill could hardly drag himself along, and when he stooped to gather a specimen he had the greatest difficulty in rising. They were never to meet again. A few days later--on the 8th May, 1873--Fabre was invited to lunch with the philosopher. Before going to the little house by the cemetery he halted, as was his custom, at the Libraire Saint-Just. It was there that he learned, with amazement, of the tragic and sudden event which set a so unexpected term to a friendship which was doubtless a little remote, but which was, on both sides, a singularly lofty and beautiful attachment. His class-books were now bringing in scarcely anything; their preparation, moreover, involved an excessive expenditure of time, and gave him a great deal of trouble; it is impossible to imagine what scrupulous care, what zeal and self-respect Fabre brought to the execution of the programme which he had to fulfil. To begin with, he considered that he could not enjoy a more splendid opportunity to give children a taste for science and to stimulate their curiosity than by finding a means to interest them, from their earliest infancy, in their simple playthings, even the crudest and most inexpensive; so true is it that "in the smallest mechanical device or engine, even in its simplest form, as conceived by the industry of a child, there is often the germ of important truths, and, better than books, the school of the playroom, if gently disciplined, will open for the child the windows of the universe." "The humble teetotum, made of a crust of rye-bread transfixed by a twig, silently spinning on the cover of a school-book, will give a correct enough image of the earth, which retains unmoved its original impulse, and travels along a great circle, at the same time turning on itself. Gummed on its disc, scraps of paper properly coloured will tell us of white light, decomposable into various coloured rays... "There will be the pop-gun, with its ramrod and its two plugs of tow, the hinder one expelling the foremost by the elasticity of the compressed air. Thus we get a glimpse of the ballistics of gunpowder, and the pressure of steam in engines..." The little hydraulic fountain made of an apricot stone, patiently hollowed and pierced with a hole at either side, into which two straws are fitted, one dipping into a cup of water and the other duly capped, "expelling a slender thread of water in which the sunlight flickers," will introduce us to the true syphon of physics.