Paris was gay, celebrating the national holiday of France, the anniversary of the storming of the Bastille in 1789. This gave me a chance to see many of the striking characteristics of the gay side of Paris in a single day. The next day, while visiting the great Sorbonne and the Collège de France in the Quartier Latin, I found a great treasure in a second-hand bookshop: La Grange’s great treatise, “Méchanique Analytique,” first published under the auspices of the French Academy in 1788. La Grange, the Newton of France! There was no student of dynamics who had not heard of his name and of his great treatise. My two months’ stay in Pornic had enabled me to appreciate fully the beauty of the language of this great work, and my training with Routh had eliminated many difficulties of the mathematical technique. I was convinced of that in my very first attempts in Paris at deciphering some of its inspiring pages. I describe this short stay in France at some length, because I wish to refer to it later for the purpose of showing how little things can exert a big influence in the shaping of human life. * * * * * I had promised my mother to visit her again during that summer, and off I went, deserting without delay the gay scenes of Paris. On my journey to Idvor I wasted no time looking to the right or to the left of my speeding train; villages and towns, rivers and mountains, and the busy folks in the yellow fields who were gathering in the blessings of the harvest season appeared like so many passing pictures which did not interest me. La Grange was talking to me, and I had neither eyes nor ears for anybody or for anything else. Oh, how happy I was when I saw Idvor in the distance, where I knew I should be free for nearly two months during that summer to read and to reflect, free from all restraints of the Cambridge routine. By the end of that heavenly vacation I had mastered a good part of La Grange’s classical treatise, and in addition I had reread carefully Campbell’s “Life of Maxwell,” and I understood many things which I had seen in Cambridge but had not understood before. The Cambridge movement described above was clearly revealed to me in the course of that summer, by a careful study of Campbell’s “Life of Maxwell.”