Lord Kelvin on quantitative knowledge

Qualitative knowledge is real, but… quantitative knowledge is almost always better.

On the importance of being able to express your beliefs about the world in mathematical terms, a venerable quote from famous 19th century physicist William Thomson, 1st Baron Kelvin. He’s worth listening to, as he’s the inventor of large swaths of thermodynamics (and, to be fair, a few silly predictions like “there is nothing new to be discovered in physics” on the eve of the quantum mechanics & relativity revolution!):

In physical science a first essential step in the direction of learning any subject is to find principles of numerical reckoning and practicable methods for measuring some quality connected with it. 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.
— Thomson, W. (1891). Popular Lectures and Addresses, Vol. I, p. 80.