“The purpose of abstraction is not to be vague, but to create a new semantic level in which one can be absolutely precise.” — Edsger Dijkstra

I've thought a lot about this quote, and the best abstractions I use are absolutely this. I love array indexing as an abstraction, but in the back of my head I have pointer + index * size. I like having the kernel do memory mapping, but I know there's a buddy allocator and TLB cache there.