Comment by mingusrude a day ago
I once watched a presentation by Dan North where he said that a microservice should never be bigger than your head. What he meant was that all the code for the microservice should fit on your screen and you should be able to put your head against the screen and it should cover the code.
Yes, this was in the microservices-heyday.
This is probably a common; lisp/scheme type of thought. Dan Friedman also said something about how he only likes code that he can hold in his head to think about in the shower. I forgot the source, but it's in one of the talks. I think Sussman has also said something similar.
Anything you create in software should be able to fit in someone else's head. I.e., you should be able to think of it as a tractable arrangement of abstractions that let you reason about it in a precise, non-leaky way.
Those abstractions don't just poof into existence after the project is complete, though. You have to design them into the system and communicate them to the people who need them.
The abstractions also need to be precise and non-leaky enough to be useful. One of the most dangerous talents in software is the ability to create the illusion of tractability by using vague language. You can create an absolute mess and then describe it to management in a way that makes it sound well-understood. This is the most lucrative and destructive skill a consultant can have.
A quote originally (AFAIK) from the wonderful book 'Practical Common Lisp'.
https://gigamonkeys.com/book/