To any one who should insist upon its being stated in terms what Pain is, it would, I hold, be a sufficient answer to say, that he knew himself perfectly well what it was already, and that he could not know it the better for any words in which it could be defined. Things which all men know infallibly by their own perceptive experience, cannot be made plainer by words. Therefore, let Pain be spoken of simply as Pain.

Peter Mere Latham, ‘General Remarks on the Practice of Medicine’, The British Medical Journal, vol. 1, no. 78 (June 28, 1862), p. 677