Everything is either a Service, Entity, or Value

First, remember that everything in your system is either a Service, Entity or Value. I didn’t make those names up: I learned them from Eric Evans in Domain-Driven Design.

https://blog.thecodewhisperer.com/permalink/when-is-it-safe-to-introduce-test-doubles

Fourth generation languages

Another is that trying to make a language syntax English-like often demands that the ``English'' it speaks be bent seriously out of shape, so much so that the superficial resemblance to natural language is as confusing as a traditional syntax would have been. (You see this bad effect in a lot of so-called ``fourth generation'' and commercial database-query languages.)

http://www.catb.org/~esr/writings/cathedral-bazaar/cathedral-bazaar/ar01s09.html

Hardest thing in Software Engineering

The hardest part of the software task is arriving at a complete and consistent specification, and much of the essence of building a program is in fact the debugging of the specification.

Brooks -- No Silver Bullet