This is a wonderful piece of writing by Marcin, ostensibly about bug-fixing but really an almost existential examination of the nature of coding.
Bugs are, by definition, a look backward—at past behavior, at code that already exists, at the old work of engineers whom you’ve never met. It can feel more fun to write new code, chart new territories, add new functionality.
But the past can be fun, too. A good bug is a puzzle. A mystery. A whodunit. To solve a bug, sometimes you have to be a scientist: observe and measure, chart out the logic, follow the math. But then, two minutes later, you need to wear a hat of a very particular detective—take your flip notepad and interview different pieces of code to understand not what they claim they do, but what they actually do.