وهي لا يجوز أن تكون نفسها
That cause cannot be the series itself.
If the collection is said to be the cause of its own existence, it must already be there as cause even though its existence is precisely what is being explained as effect. This is the circularity at issue in the causal relation.
To say “this building exists because the same building is the foundation of its own existence” gives no non-circular explanation. Simply naming the collection cannot replace an account of its existence.