"The understanding, like the eye, whilst it makes us see and 
    perceive all other things, takes no notice of itself; and 
    it requires art and pains to set it at a distance and make
    it its own object."

   "He that attentively considers the state of a child, at his
    first coming into the world, will have little reason to 
    think him stored with plenty of ideas, that are to be the 
    matter of his future knowledge. It is _by degrees_ he comes
    to be furnished with them."

   "... but yet, I think, it will be granted easily, that if a
    child were kept in a place where he never saw any other but 
    black and white till he were a man, he would have no more
    ideas of scarlet or green, than he that from his childhood
    never tasted an oyster, or a pineapple, has of those 
    particular relishes."

   "To ask, at what time a man has first any ideas, is to ask, 
    when he begins to perceive; -- having ideas, and perception,
    being the same thing."

   "To say a notion is imprinted on the mind, and yet at the 
    same time to say, that the mind is ignorant of it, and 
    never yet took notice of it, is to make this impression
    nothing."

    - John Locke, An Essay Concerning Human Understanding, Book I

John Locke Resources on the Web:

John Locke Timeline - A comprehensive timeline of the life and 
work of John Locke, as well as several quotes and links to 
further sources of information.
http://www.orst.edu/instruct/phl302/philosophers/locke.html

John Locke: Works - A collection of John Locke's works 
available on the World Wide Web.
http://weber.ucsd.edu/~dmckiern/locke.htm