Hello everyone! As an admirer of string theory, I have strong interest in the theories that purport to unify general relativity with quantum mechanics. In the case of string theory, the goal is to find a form of describe the force of gravity according to the principles of quantum mechanics, ie, we start from quantum mechanics to later incorporate general relativity. My question lies at this point. It is possible from the general relativity reach a ToE? What are the reasons to try the first approach? What are the theories that use this approach? I once heard in a documentary that one reason for Einstein's failure to find a ToE was just to have opted for this approach. This fact proceeds? Is possible to perform the reverse path of string theory? I appreciate any response and apologize for any theoretical errors contained in my question.