He is told there is much to learn through listening and study (the words in the old Greek for both types of learning are different); but much he will never know. The goddess makes an important point: that knowledge is not being withheld from him.
The worlds of Night and Day are contraries, but this does not imply separation. Otherwise there would be no twilight.
It is vital to make distinctions - but foolish to assume separation.
So the youth exists between mortal and god. But there is no implied division.