John Locke, "Of Ideas in General, and their Original":

Sec. 2: Let us then suppose the Mind to be, as we say, white Paper, void of all Characters, without any Ideas; How comes it to be furnished? Whence comes it by that vast store, which the busy and boundless Fancy of Man has painted on it, with an almost endless variety? Whence has it all the materials of Reason and Knowledge? To this I answer in one word, From Experience.: In that, all our knowledge is founded; and from that it ultimately derives it self. Our Observation employed either about external, sensible Objects; or about the internal Operations of our Minds, perceived and reflected on by our selves, is that, which supplies our Understanding with all the materials of thinking. These are the two Fountains of Knowledge, from whence all the Ideas we have, or can naturally have, do spring.

from An Essay Concerning Human Understanding (1690).