Even the smartest programmer will eventually fail to understand every detail and implication of a system due to cognitive load limits, and thus bugs. Which is

Even the smartest programmer will eventually fail to understand every detail and implication of a system due to cognitive load limits, and thus bugs. Which is why languages that feature less cognitive load to understand (such as functional immutable languages) are a better direction for tomorrow’s code. If a function called from your known scope cannot modify anything you pass to it, that’s an entire class of bugs made impossible to create.