Can anyone give me a relatively simple proof or Some reference for the following fact.(I know that there is a proof of this theorem in Gerard J. Murphy'book: "C*-Algebras and Operator Theory", but I'm sure that there should be a simple proof of this.

**Every hereditary C*-subalgebra of a simple C*-algebra is also simple!**

Maybe this is easy for someone, but it makes me confused for a long time. I am a novice!