Boyle (1627–1691) claimed that the things in the world studied in physics, chemistry, biology, and inquiries into gases and fluids were all made up of atoms. He thought that because atoms could be used to explain and predict what was observable, their existence was an empirical matter and not the results of pure speculation. Unlike Gassendi, who was content to suspend judgment on whether atoms existed, Boyle claimed that atoms did exist, using the method of transdiction.