The greatest chemist of the 18th century, author of what would become known as Lavoisier's Law - "nothing is lost, nothing is created, everything is transformed." Lavoisier also made significant contributions to the science of combustion, including the identification of oxygen and hydrogen, and his pioneering work on the list of elements. No one would better explain the world until Einstein. In terms of the Revolution, Lavoisier was a supporter of new philosophical ideas and a new social order (he called for the creation of social insurance and retirement funds for the elderly, the abolition of all forced work for peasants, as well as freedom of trade). Both before and during the revolution, he served on the Gunpowder Commission which greatly improved the quality of French munitions. However, as a former member of the Ferme Générale (a private tax-collecting system under the monarchy), Lavoisier fell afoul of the radical revolutionaries and was declared a traitor by the Convention. In 1794, upon his arrest, Lavoisier, who had been conducting an experiment in his laboratory at the Royal Arsenal, requested a few days more to continue his work. The judge refused: "The Republic needs neither scientists nor chemists," before sending him to guillotine. Lavoisier's wife Marie-Anne worked alongside her husband in the laboratory as translator and assistant. She is largely responsible for securing his legacy as a scientist after the Revolution.