Board Thread:Questions and Answers/@comment-7708862-20130402005255/@comment-7708862-20130403165859

Ulquiorra said it: the release of power could threathen las noches existence. So the release of number 4 and higher could destroy it. Simple logic: number 4 release: threathening number 0 release: absolutely destroying las noches Because power difference is huge between up following numbers.

Also if you would use reverse logic: number 0 release: only threathens las noches then number 4's release would be harmless bcs of the power difference