reading the Posterior Analytics

"All teaching and all intellectual learning come about from already existing knowledge." (first sentence of the Posterior Analytics)

I still haven't figured out how this can possibly be correct. Wouldn't you have to learn the particulars in order to learn universals through induction? The particulars are not all clear from the moment of your birth, and neither deduction nor induction could account for your coming to know the particulars (deduction could if you already knew the universals, but since we're talking about particulars from which an induction to a universal is possible, the universal will have to wait. Therefore, you must learn the particulars in some other way than induction or deduction. But what way is there of learning on the basis of prior knowledge besides induction and deduction? And what prior knowledge, for that matter, could be involved in learning a particular?

I realize this is an obvious and probably superficial objection, and that fifty eminent scholars have explained it somewhere but do you see me sitting on top of an already read stack of fifty eminent scholars' writings on the Posterior Analytics? I have a hard enough time getting through one article in a week.