When my mother took his advice, she listened with the greatest respect. She thought it natural that he did not perform certain duties which, for us, were obligatory. We had not the same duties. This idea was not formulated then in my childish brain with this positive distinctness, but it developed there the germ of that which later became one of the convictions of my youth--to know that the same rules do not govern intellectual minds that control other men. It was there in that little church, quietly bending over my prayer book, that the great principle of my life had birth, not to consider as a law for thinking men that which is and ought to be a law for others--just as I received from the conversations with my father, during our excursions, the first germs of my scientific view of the world. The country around Clermont is marvelous, and although I am the reverse of poetical, a man for whom the external world means very little, I have always retained in my memory the pictures of the landscapes which surrounded these walks. While the city on one side looks toward the plain of the Limagne, on the other it stands on the foothills of the Dôme Mountains. The slope of the extinct craters, the undulations caused by old eruptions and the streams of hardened lava give to the outlines of these volcanic mountains a resemblance to the landscapes in the moon as discovered by the telescope in that dead planet. On one side is the savage and sublime memorial of the most terrible convulsions of the globe, and on the other the prettiest rusticity of stony roads among the vineyards, of murmuring brooks under the willows and chestnuts. The great pleasures of my childhood were the interminable wanderings with my father in all the paths which lead from the Puy de Crouël to Gergovie, from Royat to Durtol, from Beaumont to Gravenoire. Simply in writing these names, my memory rejuvenates my heart. I see myself again the little boy, whom a portrait represents with long hair, with his legs in cloth leggings, who walks along holding his father’s hand. Whence came this love for the fields to him, the learned mathematician, the man of study and of reflection? I have often thought of it since, and I believe I have discovered a law of the development of mind;--our youthful tastes persist even when we are developed in a sense contrary to them, and we continue to exercise these tastes while justifying them by intellectual reasons which would exclude such things.