It happened the usual way: I had an interesting conversation, I realized something fundamental, and decided to write an article about it here on WIP. No different today. Conversation, realization, article.
Although it's not exactly a novel idea - that human is half an animal and half a god. Nietzsche realized it. Rank realized it. After all, humans are physiologically very similar to wild animals. It's the consciousness part, the utterly weird and unnecessary attribute to humans specifically, that separates us from other animals, and makes us creatures that create things that aren't at all essential for survival.
In the process of creating a set of rules for yourself to follow, you're reaching into the god in you; moving closer to the idea that Nietzsche called the Übermensch; and leaving behind bits of the mere animal that isn't interested in integrity, rules, or honor, but only in living through the day and propagating. You're the maker of your own laws. You're your own authority.
However, at times - often, even - you find yourself suffocated by the rules you created for yourself. You rebel against your own laws, against yourself. You want to prove you're not a piano key, and so you abandon all the rules and embrace the aspects of your animal half once again.
Only to get fed up with the pettiness of it, and to create a rule system for yourself to abide by. The cycle starts over.
There's nothing fundamentally wrong with this phenomenon. It's both the burden and the gift of being human. You can neither be content with being a mere animal, nor blindly accept the absolutism of a random set of principles.
The cycle that human nature itself forces us to endure is there to allow us to see the value in both extremes.