Why do we say "TouchWood"

We say good things, we say bad things. What matters are the better things that we say.
Even you might have said a very good thing once, might be when you compliment something or just casually (who needs a special time to say a good thing!). And while you're at it, you might have used the word "touch wood".
Ever thought what this simple 2 word phrase meant when used in the context?
The word Touch Wood has been in use in mainly India, UK, Ireland and Australia. While other parts of the world use the phrase "Knock on Wood".
Actually, in older days, people used to have a belief that Gods dwell in trees. So, touching a tree was like having God's hand on them, protecting them from bad omens etc. So, when somebody would say something that would boast or just say something, it was and is believed that the evil would start to eye them. Then, touching a tree or 'wood' would ward off the evil! That's how Touchwood literally means the act of touching wood.
Now that you why, Touchwood!