Suppose that [an ordinary day-labourer] meets with a modern philosopher, and wants to be informed, what smell in plants is. The philosopher tells him, that there is no smell in plants, nor in any thing but in the mind: that it is impossible there can be smell but in a mind; and that all this hath been demonstrated by modern philosophy. The plain man will, no doubt, be apt to think him merry: but if he finds that he is serious, his next conclusion will be, that he is mad; or that philosophy, like magic, puts men into a new world, and gives them different faculties from common men. And thus philosophy and common sense are set at variance. But who is to blame for it? In my opinion the philosopher is to blame. For if he means by smell what the rest of mankind most commonly mean, he is certainly mad. But if he puts a different meaning upon the word, without observing it himself, or giving warning to others, he abuses language, and disgraces philosophy, without doing any service to truth: as if a man should exchange the meaning of the words daughter and cow, and then endeavour to prove to his plain neighbour, that his cow is his daughter, and his daughter his cow.
This, from An Inquiry into the Human Mind: on the Principles of Common Sense (1764), is à propos some smug public assertion that 'water is not wet'.