Robert Boyle, FRS, (25 January 1627 – 31 December 1691) was an Irish 17th-century natural philosopher, chemist, physicist, and inventor. Born in Lismore, County Waterford, Ireland, he was also noted for his writings in theology. Although his research clearly has its roots in the alchemical tradition, Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of modern chemistry, and one of the pioneers of modern experimental scientific method. He is best known for Boyle's law, which describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system. Among his works, The Sceptical Chymist is seen as a cornerstone book in the field of chemistry.