All four of those are great! But if they are wrong, then it is still wrong no matter how simple.

Like saying leap years occur every four years. Simple!

I think I read the OP's assertion in relation to your counterpoint like this: when thinking through the problem, your initial iteration of work is allowed to say exactly that: a leap year occurs every 4 years. However, you should do so via a semi-stubbed function (isLeapYear) as mentioned previously. I am imagining that the specifics of when a leap year occurs are not critical to your solution, only that you know when they happen. Thus, you avoid spending too much time on a detail that's eventually important, but not critical for proving your first hypothesis. In the "correct" stage you come back and improve the isLeapYear function to return correct results.

Part of attaining wizard status is not learning how to hold more of the program in your head, but instead learning how to hold _less_. This seems like an excellent step in that direction.

The author assumes that simplicity is a prerequisite for correctness which is in general true but it does not say when exactly a simple system is turned into a complex system. I would say that if the complexity of your system is still under control then it is qualified as a simple system.

I would say that the last one places correctness first.

BTW, the quote is usually attributed to Einstein, but it seems he did't say it.