The Sceptical Chymist or Chymico-Physical Doubts & Paradoxes is the title of Robert Boyle's masterpiece of scientific literature, published in London in 1661. In the form of a dialogue, the Sceptical Chymist presented Boyle's hypothesis that matter consisted of atoms and clusters of atoms in motion and that every phenomenon was the result of collisions of particles in motion. He appealed to chemists to experiment and asserted that experiments denied the limiting of chemical elements to only the classic four: earth, fire, air, and water. He also pleaded that chemistry should cease to be subservient to medicine or to alchemy, and rise to the status of a science. Importantly, he advocated a rigorous approach to scientific experiment: he believed all theories must be proved experimentally before being regarded as true. For these reasons Robert Boyle has been called the founder of modern chemistry..
The Sceptical Chymist is well written, enlivened with touches of humour, as when the alchemists are compared with "the Navigators of Solomon's Tarshish Fleet, who brought home … not only Gold, and Silver, and Ivory, but Apes and Peacocks too", since their theories "either like Peacock's feathers make a great shew, but are neither solid nor useful; or else, like Apes, if they have some appearance of being rational, are blemish'd with some absurdity or other which makes them appear ridiculous." The chief value of The Sceptical Chymist, aside from its main message, was the wealth of chemical experiment that showed the chemist how to employ standard terms and nomenclature in chemical explanation and also presented new chemical fact.