"We have promised each other (is it not true?) to have, the one for the other, at least a great affection. Provided that you do not change your mind! For there are no promises which hold; these are things that do not admit of compulsion. "It would, nevertheless, be a beautiful thing in which I hardly dare believe, to pass through life together hypnotized in our dreams: your dream for your country; our dream for humanity; our dream for science. Of all these dreams, I believe the last, alone, is legitimate. I mean to say by this that we are powerless to change the social order. Even if this were not true we should not know what to do. And in working without understanding we should never be sure that we were not doing more harm than good, by retarding some inevitable evolution. From the point of view of science, on the contrary, we can pretend to accomplish something. The territory here is more solid and obvious, and however small it is, it is truly in our possession. "I strongly advise you to return to Paris in October. I shall be very unhappy if you do not come this year, but it is not my friend's selfishness that makes me ask you to return. I ask it because I believe you will work better here and that you can accomplish here something more substantial and more useful." One can understand, from this letter, that for Pierre Curie there was only one way of looking at the future. He had dedicated his life to his dream of science: he felt the need of a companion who could live his dream with him. He told me many times that the reason he had not married until he was thirty-six was because he did not believe in the possibility of a marriage which would meet this, his absolute necessity. When he was twenty-two years old he wrote in his diary: "Women, much more than men, love life for life's sake. Women of genius are rare. And when, pushed by some mystic love, we wish to enter into a life opposed to nature, when we give all our thoughts to some work which removes us from those immediately about us, it is with women that we have to struggle, and the struggle is nearly always an unequal one. For in the name of life and of nature they seek to lead us back." We can see, however, in the letters I have quoted earlier, the unshakeable faith that Pierre Curie had in science and in its power to further the general good of humanity. It seems appropriate to apply to him the sentiment expressed by Pasteur in words so well known: "I believe invincibly that science and peace will triumph over ignorance and war." This confidence in the solutions of science made Pierre Curie little inclined to take an active part in politics. He was attached, by education and by conviction, to democratic and socialistic ideas, but he was not dominated by any party doctrine. However, he always fulfilled, as his father did, his obligations as a voter. In public life, as in private life, he was opposed to the use of violence.