Marco Arment has a great piece looking back on his time at Tumblr, and giving us a look inside.

David always had a vision for where he wanted to go next. I was never the “idea guy” — in addition to my coding and back-end duties, I often served as an idea editor. David would come in with a grand new feature idea, and I’d tell him which parts were infeasible or impossible, which tricky conditions and edge cases we’d need to consider, and which other little niceties and implementation details we should add. But the ideas were usually David’s, and the product roadmap was always David’s.

Read the whole piece. It’s incredibly interesting.