Answer: to explain to children that the moon causes the tides
Step-by-step explanation:
In this children's book creation story , the Eldest Magician created the Earth as it is and told the animals what their roles were in the form of plays.
The Fisherman in this tale is meant to symbolize the moon and how it can cause waves by showing that it pulls the waters along as it travels. The Eldest Magician as custodian of the Earth saw this and charged him to do so twice a day and twice at night to make seafaring easier for fishermen.
This is to show children that the moon is responsible for waves.