Electrical units of measurement

William Thomson

I often say that 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.

Fonte (em port.): Vianna, H. M. 1978. Testes em educação, 3ª ed. SP, Ibrasa. Excerto de livro publicado em 1889. O autor é mais comumente referido como Lorde Kelvin.