All ideas come from experience.

 So, at birth, the human mind is a sort of blank slate on which experience writes. In Book II Locke claims that ideas are the materials of knowledge and all ideas come from experience.

Locke has an atomic or perhaps more accurately a corpuscular (bodily) theory of ideas.

There is, that is to say, an analogy between the way atoms or corpuscles combine into complexes to form physical objects and the way ideas combine. Ideas are either simple or complex. We cannot create simple ideas, we can only get them from experience. In this respect the mind is passive.

Locke