9867. 'And the second row' means this group of three also existing as one. This is clear from what has been shown immediately above. In general every unified whole arises from the harmony and agreement of many constituent parts, see 457.

457. Nearly everyone who enters the next life from the world imagines that hell is the same for everybody, and that heaven is too, when in fact there are limitless differences and variations in both. Hell is never exactly the same for one person as it is for another, and neither is heaven, just as one man, spirit, or angel is never given to be exactly like another. At my merest thought of two being exactly alike or equal, people in the world of spirits and those in the angelic heaven were horrified. They said that every unified whole is formed from the harmony of many constituent parts, and that that whole depended on this harmony. Indeed a simple whole cannot possibly exist, only a harmonized whole. Every community in heaven forms a whole in this way, and all the communities, that is, heaven in its entirety, form a whole. And all this derives from the Lord alone by means of love. A certain angel was counting up merely the most general classes of joy found among spirits, that is, among members of the first heaven. They came to about four hundred and seventy-eight. This demonstrated how countless the less general classes must be and how innumerable the divisions within each class. And with so many in the first heaven alone, how limitless must be the classes of happiness in the heaven of angelic spirits, and still more in the heaven of angels!