If you spin a raw egg, like you would a top, then stop it and leave go, it will keep on spinning.
Busy days at work have a similar effect on my brain. Things must be quiet back home, so that I can concentrate on anything meaningful outside of the daily grind. No such luck this evening, when there's a wife and two children at hand - the brain yolk just keeps on rotating.
It's a shame really, as I had a rather nice post in mind. It would have took some serenity to formulate however, so it'll have to wait for another night.