[GregDavidson]

I started with Fortran 2 which has subroutines which don't behave as black boxes. It took me months of frustrated study to understand procedure calls in decent languages as delegation. That opened up the world of high-level computing. Later I would teach this using problems that were a good fit for "recursion". Recursion is not a feature, it's just an obvious pattern of the more general and important nature of delegation. While recursion is occasionally a useful technique, it's tremendously valuable as a tool for learning how to think about procedures as black boxes!