“I know what the word [| ]toothache[| ] means, it makes me concentrate my attention on some one particular thing.” But on what? You're now inclined to give criteria of behaviour. Ask yourself: “what does the word ‘feeling’ or still better ‘experience’ make you concentrate on?”, “What is it like to concentrate on experience? If I try to do this I, e.g., open my eyes particularly wide & stare.