No inflow is possible from the lower heavens into the higher, because this is contrary to order; but there is inflow from the higher heavens into the lower. Moreover, the wisdom of the angels of a higher heaven surpasses the wisdom of the angels of a lower heaven as a myriad to one; and this is another reason why the angels of a lower heaven cannot converse with those of a higher heaven; and in fact when they look towards them they do not see them, the higher heaven appearing like a cloudy something over their heads. But the angels of a higher heaven can see those in a lower heaven, although if permitted to talk with them they would lose their wisdom, as has been said above.
The thoughts and affections as well as the speech of the angels of the inmost heaven are never perceived in the middle heaven, because they so transcend what is there. But when it pleases the Lord there is seen in the lower heavens from that source something like a flame, and from the thoughts and affections in the middle heaven there is seen in the outmost heaven something luminous, and sometimes a cloud glowing white and variegated. From that cloud, its ascent, descent, and form, what is being said there is in some measure known.2
From all this it can be seen what the form of heaven is, namely, that it is the most perfect of all in the inmost heaven; in the middle heaven it is also perfect, but in a lower degree, and in the outmost heaven in a degree still lower; also that the form of one heaven has its permanent existence from another by means of inflow from the Lord.
But what communication by inflow is cannot be understood unless it is known what degrees of height are, and how they differ from degrees of length and breadth. What these different degrees are may be seen above (Section 38).
from Heaven and Hell, Sections 209-211
Section 38: Published 7/6/2017