Arcana Coelestia #7890
7890. 'From the first day until the seventh day' means a holy and complete state. This is clear from the meaning of 'seven days' as a holy state, dealt with above in 7885, and also as a complete state, 6508. The same is also meant by 'a week', 1 and 'a week' is a whole period, long or short, from beginning to end, see 2044, 3845.
Fusnotat:
1. A week may describe a period of seven days, seven years, or seven ages.