Augustine of Hippo

(Con. Evang. iii. 24) What Luke expresses by very early in the morning, and John by early when it was yet dark, Mark must be understood to mean, when he says, very early in the morning, at the rising of the sun, that is, when the sky was growing bright in the east, as is usual in places near the rising sun; for this is the light which we call the dawning. Therefore there is no discrepancy with the report which says, while it was yet dark. For when the day is dawning, the remains of darkness lessen in proportion as the light grows brighter; and we must not take the words very early in the morning, at the rising of the sun, to mean that the sun himself was seen upon the earth, but as expressing the near approach of the sun into those parts, that is, when his rising begins to light up the sky.