The given principle is one of the postulates of Dalton's atomic theory given in 1803 by John Dalton. The postulates of Dalton's atomic theory are as follows: 1. Elements consist of indivisible small particles (atoms). 2. All atoms of the same element are identical; different elements have different types of atom. 3. Atoms can neither be created nor destroyed. 4. 'Compound elements' (i.e. Compounds) are formed when atoms of different elements join in simple ratios to form 'compound atoms' (i.e. Molecules).