"So, when on one side you hoist in Locke's head, you go over that way; but now, on the other side, hoist in Kant's and you come back again; but in very poor plight. Thus, some minds for ever keep trimming boat. Oh, ye foolish! throw all these thunder-heads overboard, and then you will float light and right." John Locke (1632-1704) was a famous British empiricist ("all knowledge comes from senses"). Immanuel Kant (1724-1804) agreed that "all knowledge begins in experience" but also said that the mind provided "a priori concepts." Melville's self-education must have been quite thorough to allow him to use these two as opposing examples.