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date: 16 April 2024

Lord Kelvin 1824–1907
British scientist 

  1. When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind: it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.
    often quoted as ‘If you cannot measure it, then it is not science’
    Popular Lectures and Addresses vol. 1 (1889) ‘Electrical Units of Measurement’, delivered 3 May 1883