The teaching is done by angels from a number of communities, mainly ones in the northern and southern regions, because these angelic communities are focused on intelligence and wisdom based on firsthand knowledge of what is good and true. The teaching sites are in the north; and there are different ones, differentiated and arranged according to the genera and species of heavenly virtues so that everyone can be taught there in a manner suited to his or her character and receptivity. The sites are spread out over a large area there.
Good spirits who need to be taught are taken there by the Lord after their time in the world of spirits has been fulfilled. This does not apply to everyone, though, since people who have been taught in the world have already been prepared for heaven by the Lord and are taken up into heaven by a different route. For some, this happens immediately after death. For others, it happens after a short stay with good spirits for the removal of the cruder elements of their thoughts and affections (acquired because of concerns for rank and wealth in the world), and their consequent purification. Some people are shattered first, which happens in sites under the soles of the feet called the lower earth, where they suffer harsh treatment. These are people who have convinced themselves of false principles but still have lived good lives. False convictions cling hard, and until they are dispelled, truths cannot be seen and therefore cannot be accepted. These shattering experiences and the different ways they happen have been treated in Secrets of Heaven, though, and some references to that work are appended in the note.
from Heaven and Hell, Section 513