In verse 37, it was said: وَآيَةٌ لَّهُمُ اللَّيْلُ نَسْلَخُ مِنْهُ النَّهَارَ‌ (And a sign for them is the night. We strip the [ cover on day from it, and they are suddenly in darkness.). After having described the signs of Divine power in what was created on the earth, the text mentions cosmic creations. The word: سَلخ (salkh) literally means to skin. If the skin from an animal or the cover from things is removed, the thing inside becomes obvious. Allah Ta’ ala has, in this similitude, pointed out that the real element in this world is darkness. Light is transitory, for it spreads over the earth through planets and stars. In a predetermined system, at a fixed time, this light that is spread over the darkness of the world is removed from on top. What remains is darkness. This, in common parlance, is called night.