High Quality Content by WIKIPEDIA articles! The origins of the metric system date back to the sixteenth century when Simon Stevin published details of his decimal notation and the seventeenth century when John Wilkins published a proposal for a decimal system of measurement based on natural units. The first practical realisation of the metric system came during the French Revolution when the existing system of measure which had fallen into disrepute was replaced by a decimal system based on the kilogram and the metre. The metric system was, in the words of Condorcet, "for all people for all time". The unit of length, the metre was based on the dimensions of the earth and the unit of mass, the kilogram, was based on the mass of water having a volume of one litre or one thousandth of a cubic metre. Reference copies for both units were manufactured and placed in the custody of the Academy of Sciences.