I believe that the tittle already covers my question, but I will explain it better here.
When I was reading the Heisig book (Remembering the Kanji, the sixth edition I believe) I came across the kanji 旦, which Heisig defines as Nightbreak. I looked at http://www.edrdg.org/cgi-bin/wwwjdic/wwwjdic?1MMJ%E6%97%A6 and found the following definition:
daybreak; dawn; morning
Which lead me thing that 旦 means the start of the day and NOT the start of the night, as the key-word and the story Heisig provides leads me to think.
But the story also talks about a more cultural aspect... I will quote the story from the book here:
While we normally refer to the start of the day as "daybreak," Japanese commonly refers to it as the "opening up of night" into day. Hence the choice of this rather odd key work, nightbreak. The single stroke at the bottom represents the floor (have a peek again at frame 1) or the horizon over which the sun is poking its head.
I know that are two different languages, but I think it it worth mentioning: I also have access to another book from Heisig, the Remembering the Simplified Hanzi (Chinese) and there the Hanzi has the meaning of daybreak; making me think that he really wants to give the kanji #30 the meaning of nightbreak.
I am super confused about this Kanji now. Can someone explain to me what is happening here regarding the meaning of the kanji and possibly give me an explanation about why Heisig chose this key word?