Nine is also a magic number- and this could be partly why cats are attributed with having nine lives, because they have been both worshipped and feared throughout the ages for being magical. The ancient Greeks said that the number nine referred to the trinity of all trinities- and is a mystic number which invokes tradition and religion.
At any rate, humans throughout the ages have been astonished at the hardiness of the feline. Cats DO almost always land on their feet. This is because they have, a ‘righting reflex’ (extremely good balance, reflexes, and very flexible backbones). As a matter of fact, they have more vertebrae than humans.
So be amazed at the nimble dexterity of our feline friends but do not expect them to have additional lives.