Open closed vs Single responsibility

I was looking into the Single Responsibility Principle(SRP) and Open Closed Principle(OCP).

SRP states that a class must have only one reason to change. OCP states that the class must be closed for modification but open to extension.

I find that to be contradicting. One principle states that the class must be simple enough, that you change for a single reason but the other principle states that a class must not be changed but only extended.

Does anyone have a better explanation?