Like other descriptions of time in the Word, "a day" or a number of "days" describe a spiritual state rather than our natural concept of time. A spiritual "day" describes a state of mind or a state in our relationship with the Lord rather than a 12-hour or 24-hour span of natural time. "Day" describes a state in which we are turned toward the Lord, and are receiving light (which is truth) and heat (which is a desire for good) from the Lord.

'The third day' as in Genesis 22:4, signifies something complete and a beginning of sanctification. 'Day,' in the Word, signifies a state, as do all references to time. When 'third' is added, it signifies the end of that state and the beginning of the following state. In the internal sense of the Word, 'three days' and 'the third day' signify the same thing. The Lord rose again on the third day, which is also why the Lord distinguished the stages of his life into three in Luke 8:32. The Lord also endured the last temptation on the cross, on 'the third hour of the day' in Mark 15:25. In Exodus 19:16, 'the third day' signifies the end of a state of preparation for reception, and so an end of purification. In Hosea 6:2, 8, 'the third day' has the same meaning as 'the seventh day,' which is a state of peace.

(References: Arcana Coelestia 8811; Luke 8; Mark 15)