The empiric easily degenerates into the quack. He does not know where his knowledge begins or leaves off, and so when he gets beyond routine conditions he begins to pretend-to make claims for which there is no justification, and to trust to luck and to ability to impose upon others-to "bluff."
The Middle Works, 1899-1924 (ed. SIU Press, 1980) - ISBN: 9780809309337