Truth is the foundation of everything and decency grounded in truth is the common thread of all justifiable will. At odds with this is the raw belief in power, which terminates in the worship of natural selection and all of it's consequences even when they are at odds with truth and decency. Much of what is called sickness is just truth that kills you. This form of sickness is infinitely more sacred than any health which undermines truth and decency. Progress is when the number of lethal truths decreases and the amount of psychopathic health decreases.

I have seen the same things as Nietzsche but rejected his assessment. The love of strength and health are still good. But they are not absolute goods. Pursued blindly they would destroy everything including themselves. This is at the heart of all perennial authoritarianism.

There is no other theory I care to profess at this time. Some are more sympathetic than others, but the root is more important than the branches.