What is the logic in a lullaby?

Question

Take for example this one.

Rock a my baby on the tree top.
When the wind blows the cradle will rock.
When the bow breaks the cradle will fall.
Down comes baby, cradle and all.

Ok, first, why would a baby on a cradle be on top of a tree. Second, you are telling the child that the bow breaks and baby, cradle and all falls. Third, there is nothing else to suggest that the baby was saved, a cradle falling on an infant would most likely kill him on impact. So what is the moral of the story or the logic. Don't put a baby on a treetop?

Answer 1

You're not the first person to ask the question (nor even the first in Yahoo! Answers). There are a number of explanations online, and many with a similar Native American theme, but some are bizarre (the final webpage listed here has a serial killer theory!). I quite like the explanation at eclipse (the 6th in the list, as it seems the most informed. You can read through the relevant sections of these webages and make your own mind up.
http://www.rhymes.org.uk/hush_a_bye_baby.htm
http://www.answers.com/topic/lullaby
http://www.answers.com/topic/rock-a-bye
http://www.abc.com.au/rn/linguafranca/stories/2005/1363912.htm
http://www.sharperiron.org/2006/12/02/broken-boughs-and-falling-cradles/
http://eclipse.rutgers.edu/goose/rhymes/baby/hush7.aspx
http://answers.yahoo.com/question/index?qid=20060814081852AACAKns
http://www.mashada.com/forums/index/show_topic/34/1182/index.php
http://www.phrases.org.uk/bulletin_board/8/messages/138.html