Two old beliefs:
Names grant special powers.
A belief that has been around for a very long time: If you know the name of a thing or of a person, you have special powers over it/him/her. In many religions the true names of gods are not known. The real name of the Egyptian god Ra, for example, was known to none, until the goddess Isis forced him to reveal his name to her.
An example from the King James Bible:
Judges 13:18 And the angel of the LORD said unto him, Why askest thou thus after my name, seeing it is secret?
Another facet of the same concept can be seen in that contracts have to be signed with one's name to become effective. Putting down your name on a piece of paper binds you to the contract. Why? Because your name is your identity. It is what you are. It is you. By signing, you bind your own identity to the contract.
It might be said that signing a contract is only for the purpose of making sure that one has seen it, and agreed with it. I believe that is not the whole of it: if you ever get to sign a contract with the devil, you put your name under it also. You give him your name and so are in his power.
Also, a name determines the character and destiny of the person bearing it.
In the middle ages it was thought that the name of a person determined his/her character and destiny. Even today expectant parents often inform themselves of the origin and meaning of the name they are going to give to their child, which is a really good idea, since it prevents naming your daughter Cassandra without knowing the meaning of the name.