Thus when an abstractive set p covers an abstractive set q, the abstractive set q inheres in every member of p.
Two abstractive sets may each cover the other.

When this is the case I shall call the two sets 'equal in abstractive force.' When there is no danger of misunderstanding I shall shorten this phrase by simply saying that the two abstractive sets are 'equal.' The possibility of this equality of abstractive sets arises from the fact that both sets, p and q, are infinite series towards their small ends.

Thus the equality means, that given any event x belonging to p, we can always by proceeding far enough towards the small end of q find an event y which is part of x, and that then by proceeding far enough towards the small end of p we can find an event z which is part of y, and so on indefinitely.
The importance of the equality of abstractive sets arises from the assumption that the intrinsic characters of the two sets are identical.
If this were not the case exact observation would be at an end.
It is evident that any two abstractive sets which are equal to a third abstractive set are equal to each other.

An 'abstractive element' is the whole group of abstractive sets which are equal to any one of themselves.

Thus all abstractive sets belonging to the same element are equal and converge to the same intrinsic character.