We now see that it was impossible because of the exact nature of the way in which the various elements combine, that chemistry could have become a science until the balance had been used to weigh the substances investigated; and we also see that it was impossible that the balance could have been so used until physics had been developed to the point permitting it, and men skilled in exact measurements had been brought up by practice in physical researches. Lavoisier himself had served a long apprenticeship, and his earliest claim to fame was his mathematical researches on heat, embodied in an essay, written in connection with Laplace, and published in 1784. Even after an enormous mass of facts had been collected and announced, chemistry could not take her place by the side of physics, and Bacon's teachings could not be followed, until those facts had been mathematically investigated, and their mathematical relations to each other had been established. This Lavoisier and his followers did. No better illustration of the influence of invention on history can be found than the fact that chemistry hovered in the dim twilight of speculation, guess-work and even superstition, until Lavoisier brought to bear the various inventions made in physics. Then, presto, the science of chemistry was born. We must not let the fact escape us, however, that Lavoisier would have left mankind none the wiser, if he had merely brought mathematical research to bear and discovered what he did, and then stopped. If he had stopped then, his knowledge would have remained locked inside of his own mind, useless. The good work that Lavoisier actually did was in actually producing an invention; in conceiving a certain definite method of chemical research, then embodying it in such a concrete form that "persons skilled in the art could make and use it," and then giving it to the world.