9534. 'And you shall make for it a rail of a hand's breadth round about' means the joining there to truth from the Divine. This is clear from the meaning of 'a rail', since this lay outside the rim, as the outermost part of the border, and so the joining to truth from the Divine. None can know that this is what 'a rail' means unless they know about the sphere of good from the Lord which surrounds and thereby protects heaven, and about the extension of and border to it. Regarding the sphere of Divine Good which surrounds heaven and all the communities in heaven and thereby protects them from the intrusion of evils from hell, see above in 9490, 9492, 9498.

[2] This Divine sphere extends even into the hells and also guards them. So it is that the Lord reigns in the hells also, yet with this difference, that the Divine sphere which surrounds and protects heaven is the sphere of Divine Truth joined to Divine Good, whereas that which guards hell is the sphere of Divine Truth separated from Divine Good. The reason why the latter sphere exists in hell is that all in that place reject Divine Good, and reject the Lord's mercy. Such a sphere reigns in outward form in hell; but still the sphere of Divine Truth joined to Divine Good does so in inward form. By means of it those in hell are guarded, so that none does excessive harm to another.

[3] From all this it is evident that the sphere of Divine Good in outward form comes to an end where heaven does so, and the sphere of Divine Truth separated from Divine Good begins where hell begins, and in the gap between there is a joining together, meant by 'the rail of a hand's breadth round about'.