Locke is determined that mind is a blank tablet, or tabula rasa. For Locke (1996: 7, 33) there are “no innate principles in the mind.” All knowledge is derived from experience:
All ideas come from sensation or reflection. 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 pointed 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 funded; and from that it ultimately derives itself.

Writing at the end of the 17th century Locke was relying on introspection rather than neuroscience. He declares (1996: 11-12) that “knowledge of some truths… is very early in the mind; but in a way that shows them not to be innate.” According to Locke:
The senses at first let in particular ideas, and furnish the yet empty cabinet: and the mind by degrees growing familiar with some of them, they are lodged in the memory, and names got to them. Afterwards the mind proceeding farther, abstracts them, and by degrees learns the use of general names. In this manner the mind comes to be furnished with ideas and language, the materials about which to exercise its discursive faculty: and the use of reason becomes daily more visible, as these materials, that give it employment.
John Locke (1996) An Essay Concerning Human Understanding, (First Published 1689) Abridged and Edited by Kenneth P. Winkler. Hackett Publishing, Indianapolis/Cambridge.