Arcana Coelestia #480
480. It is clear from Genesis 1:26-27 as well, that 'they were called Man on the day in which they were created', that is to say, at the end of the sixth day, which answers to the evening of the Sabbath, or start of the Sabbath or seventh day. For as shown already, the seventh day or Sabbath is the celestial man.
Dark
Darkness" is a state without light. "Light" is truth from the Lord, so "darkness" represents a state where truth is lacking. Here's a cogent passage from Arcana Coelestia: "The person who has yet to be regenerated is called 'a void and an empty earth', and also 'ground', in which no good or truth at all has been sown - 'void' where there is no good, and 'empty' where there is no truth. Consequently there is 'thick darkness', or stupidity and lack of knowledge about anything that has to do with faith in the Lord and so anything that has to do with spiritual and celestial life. (Arcana Coelestia 17)