Arc Of Ascension and Arc Of Descension

What are the three darkness’s in the words of Allah:
“He created you from one being, then from that (being) He made its mate; and He hath provided for Resurrection you of cattle eight kinds. He created you in the wombs of your mothers, creation after creation, in a threefold darkness. Such is Allah, your Lord. His is the Sovereignty. There is no God save Him. How then are ye turned away?”