Genesis: "God called the light day and darkness he called light." But wait...that was in Hebrew. Hang on then:
O.E. dæg, from P.Gmc. *dagaz, from PIE *dhegh-. Not considered to be related to L. dies (see diurnal), but rather to Skt. dah "to burn," Lith. dagas "hot season," O.Prus. dagis "summer." Meaning originally, in Eng., "the daylight hours," expanded to mean "the 24-hour period" in late O.E. Daydream is 1685 (n.), 1820 (v.). Day off first recorded 1883; day-tripper first recorded 1897; daylight in slang sense of "clear open space between two things" is from 1820. Day-Glo is 1951, proprietary name (Dane & Co. of London) for a brand of fluorescent paint. The days in nowadays, etc. is a relic of the O.E. and M.E. use of the adverbial genitive.
O.E. niht (W.Saxon neaht, Anglian næht, neht), the vowel indicating that the modern word derives from oblique cases (gen. nihte, dat. niht), from P.Gmc. *nakht- (cf. O.H.G. naht, O.Fris., Du., Ger. nacht, O.N. natt, Goth. nahts), from PIE *nok(w)t- (cf. Gk. nuks "a night," L. nox, O.Ir. nochd, Skt. naktam "at night," Lith. naktis "night," O.C.S. nosti, Rus. noch', Welsh henoid "tonight"). For spelling with -gh- see fight.
"The fact that the Aryans have a common name for night, but not for day (q.v.), is due to the fact that they reckoned by nights." [Weekley]
Cf. Ger. Weihnachten "Christmas." In early times, the day was held to begin at sunset, so O.E. monanniht "Monday night" was the night before Monday, or what we would call Sunday night. Nightclub "club open at night" is from 1894; nightspot in the same sense is from 1936. Nightstick (1887) so called because it was carried for night patrols. To work nights preserves the O.E. genitive of time. Night shift is attested from 1710 in the sense of "garment worn by a woman at night" (see shift); meaning "gang of workers employed after dark" is from 1839. Night soil "excrement" (1770) is so called because it was removed (from cesspools, etc.) after dark.
That bit from Genesis should read, "The darkness he called NIGHT. Sheesh.