To prove light Allah created its antonym darkness. (On that analogy) dark night and bright day were created. But since Allah has nothing contrary to Him simply because He is unimaginable, nothing by way of contrast can be put up to prove Him. In the Realm of His individuality nothing exists outside of Him by way of colour or form.
پس بضد نور وانستی تو نور
ضد ضد را می نماید در صدور
پس نہانیہا بضد پیدا شود
چونکہ حق رانیست ضد پنہاں بود
(Roomi)
Hence by the opposite of light you came to know light. By its appearance a contrary proves its opposite. Accordingly the hidden things are known only through their opposite; and since Allah has nothing contrary to Him, He remains a paradox.
Note: (1) According to Moulana Roomi, light is known by contrasting it with darkness and pleasure is known through the pain. But God is the sum total of all existence and nothing stands outside of Him by contrasting with which He could be known (Metaphysis of Roomi by Dr. Khalifa).
(2) A member of the Shamsul Arfin family in Bukhara had told Shah Shakar Ganj that there were 70000 veils of darkness between him and Allah, and when they were drawn off one by one he saw himself alone behind them in a purely white background. “Begum Sufia” by Syed Salahuddin.

Dark is the night, bright is the day, that is light's attribute,
Dark night and bright day, is the of physical universe,
There is neither colours nor from, in loved one's presents.