[jey]

  There are only two hard things in Computer Science: cache invalidation and
  naming things.
  
  -- Phil Karlton

https://martinfowler.com/bliki/TwoHardThings.html

[andrewstuart2]

Aw, you didn't quote the best one from that page.

"There are 2 hard problems in computer science: cache invalidation, naming things, and off-by-1 errors."

[kornish]

Haha, didn't see that you beat me to it.

It's worth including the third saying on the page just for completeness:

"There are only two hard problems in distributed systems: 2. Exactly-once delivery 1. Guaranteed order of messages 2. Exactly-once delivery"

[kornish]

"There are 2 hard problems in computer science: cache invalidation, naming things, and off-by-1 errors."