The Soul begins to have Ideas when it begins to perceive.
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. I know it is an opinion, that the soul always thinks, and that it has the actual perception of ideas in itself constantly, as long as it exists
 John Locke, An Essay Concerning Human Understanding (1689). copy citation

Context

“and so growing up in a constant attention to outward sensations, seldom make any considerable reflection on what passes within them, till they come to be of riper years; and some scarce ever at all. 9. The Soul begins to have Ideas when it begins to perceive. 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. I know it is an opinion, that the soul always thinks, and that it has the actual perception of ideas in itself constantly, as long as it exists; and that actual thinking is as inseparable from the soul as actual extension is from the body; which if true, to inquire after the beginning of a man’s ideas is the same as to inquire after the beginning of his soul.” source