"To deafen with little bells the spirit that would think."
"In order that, weak one that I am, I shall not let my head turn with all the winds, yielding to the least breath that touches it, it is necessary that all should be immobile about me, or that, like a spinning top, movement alone should render me insensible to external objects.
"When, in the process of turning slowly upon myself, I try to gain momentum, a nothing, a word, a story, a paper, a visit stops me and is able to put off or retard forever the moment when, granted a sufficient swiftness I might have, in spite of my surroundings, concentrated on my own intention.... We must eat, drink, sleep, be idle, love, touch the sweetest things of life and yet not succumb to them. It is necessary that, in doing all this, the higher thoughts to which one is dedicated remain dominant and continue their unmoved course in our poor heads. It is necessary to make a dream of life, and to make of a dream a reality."
This acute analysis, sufficiently surprising in a young man of twenty years, suggests in an admirable manner the conditions necessary to the highest manifestations of the intellect. It carries a lesson which, if it were sufficiently understood, would facilitate the way of all contemplative spirits capable of opening new paths for humanity.
The unity of thought toward which Pierre Curie strove was troubled not only by professional and social obligations but also by his tastes, which urged him towards a broad literary and artistic culture. Like his father, he loved reading, and did not fear to undertake arduous literary tasks. To some criticism made in this connection, he responded readily: "I do not dislike tedious books." This meant that he was fascinated by the search after truth which is sometimes associated with writing devoid of charm. He also loved painting and music, and went gladly to look at pictures or to attend a concert. A few fragments of poetry in his handwriting were left among his papers.
But all these preoccupations were subordinated in his mind to what he considered his true task, and when his scientific imagination was not in full activity, he felt himself, in a sense, an incomplete being. He expressed this inquietude with an emotion born of his suffering during momentary periods of depression.
"What shall I become?" he wrote. "Very rarely have I command of all myself; ordinarily a part of me sleeps. My poor spirit, are you then so weak that you cannot control my body? Oh, my thoughts, you count indeed for very little! I should have the greatest confidence in the power of my imagination to pull me out of the rut, but I greatly fear that my imagination is dead."
But despite hesitations, doubts, and lost moments, the young man was little by little striking out his path and strengthening his will. He was resolutely carrying on fruitful investigations at an age when many men who were to become savants were as yet only pupils.
His first work, done in collaboration with Desains, concerned the determination of the lengths of heat waves with the aid of a thermoelectric element and a metallic wire grating, a process, then entirely new, which has since often been employed in the study of this question.
Following this he undertook an investigation on crystals in collaboration with his brother, who had passed his licentiate and was preparator for Friedel in the laboratory of mineralogy at the Sorbonne. Their experiments led the two young physicists to a great success: the discovery of the hitherto unknown phenomena of piezo-electricity, which consists of an electric polarization produced by the compression or the expansion of crystals in the direction of the axis of symmetry. This was by no means a chance discovery. It was the result of much reflection on the symmetry of crystalline matter, which enabled the brothers to foresee the possibilities of such polarization. The first part of the investigation was made in Friedel's laboratory. With an experimental skill rare at their age, the young men succeeded in making a complete study of the new phenomenon, established the conditions of symmetry necessary to its production in crystals, and stated its remarkably simple quantitative laws, as well as its absolute magnitude for certain crystals. Several well-known scientists of other nations (Roentgen, Kundt, Voigt, Riecke) have made further investigations along this new road opened by Jacques and Pierre Curie.
The second part of the work, and much more difficult to realize experimentally, concerned the compression resulting in piezo-electric crystals when they are exposed to the action of an electric field. This phenomenon, foreseen by Lippmann, was demonstrated by the Curie brothers. The difficulty of the experiment lay in the minuteness of the deformations that had to be observed. Fortunately Desains and Mouton placed a small room adjoining the physics laboratory at the disposal of the brothers so that they might proceed successfully with their delicate operations.