section_path: History of the concept/Isaac Watts
section_name: Isaac Watts
paragraph_text: Isaac Watts
  
  In his Logick, published in 1724, the English minister and logician Isaac Watts gave an early definition of chemical element, and contrasted element with chemical compound in clear, modern terms.
  
  Among Substances, some are called Simple, some are Compound... Simple Substances... are usually called Elements, of which all other Bodies are compounded: Elements are such Substances as cannot be resolved, or reduced, into two or more Substances of different Kinds.... Followers of Aristotle made Fire, Air, Earth and Water to be the four Elements, of which all earthly Things were compounded; and they suppos'd the Heavens to be a Quintessence, or fifth sort of Body, distinct from all these : But, since experimental Philosophy... have been better understood, this Doctrine has been abundantly refuted. The Chymists make Spirit, Salt, Sulphur, Water and Earth to be their five Elements, because they can reduce all terrestrial Things to these five : This seems to come nearer the Truth ; tho' they are not all agreed... Compound Substances are made up of two or more simple Substances... So a Needle is simple Body, being made only of Steel; but a Sword or a Knife is a compound because its... Handle is made of Materials different from the Blade.