Comment by Pxtl

When you're writing it you have the help of the compiler and various other tools, plus you have the model of what the code is doing fully-formed in your head, and you have the recent memory of various other approaches you took and how and why they failed. When you're reading it you have none of those things.

So, code is harder to read than it is to write.

So if you write code that uses your full intellect to write it out, you are therefore by definition too dumb to read it.