What does This Quote Really Mean.?

Question

Keep your friends close, but enemies closer.

I mean what is the deep definition, and give example.

Example to me really counts, too.

Answer 1

It means that it is good that you keep in close contact with your friends but it is better to keep an even closer watch on your enemies because you never know when they are going to stab you in the back.  Always know what they are doing so

they cannot catch you off guard.