I think the major good idea in Unix was its clean and simple interface: open, close, read, and write.
One is that the perfect garden can be created overnight, which it can't.
One of my most productive days was throwing away 1,000 lines of code.
No amount of source-level verification or scrutiny will protect you from using untrusted code.
It's always good to take an orthogonal view of something. It develops ideas.
The steady state of disks is full.