section_path: History of the concept/Momentum/John Wallis
section_name: John Wallis
paragraph_text: John Wallis
  
  In 1670, John Wallis, in Mechanica sive De Motu, Tractatus Geometricus, stated the law of conservation of momentum: "the initial state of the body, either of rest or of motion, will persist" and "If the force is greater than the resistance, motion will result". Wallis used momentum for quantity of motion, and vis for force.