ANTOINE LAURENT LAVOISIER is heralded as the founder of modern chemistry whose genius was cut short by the brutal Revolutionary terror of the French Revolution. "Only a moment to chop off that head," said Lagrange the mathematician to Delambre, one of the inventors of the metric system, "and a hundred years may not give us another like it." Until Antoine Lavoisier, all matter was believed to be composed of four elements: earth, water, air and fire. It was Lavoisier who first showed that Nature was made out of much more complicated stuff, and that bodies burn not by releasing their fire element, but by combining with the element oxygen, the same element that enables plants and animals to breathe.