Viking see, Viking memorize. That’s how Vikings learn things. They see something, and then they memorize it. Quite simple, really.
It can also mean awake. Just remember that a viking can't see if it isn't awake. There won't be anything to memorize if their eyes are still closed, after all!
Every morning, a cock (かく) crows and rouses the Vikings. Seeing this, one of the Vikings memorizes the cock crow so that he can mimic it and play pranks on his fellow Vikings.