Yep.
'116. You think you know when you can learn, are more sure when you can write, even more when you can teach, but certain when you can program.'
"Epigrams in Programming", by Alan J. Perlis; ACM's SIGPLAN publication, September, 1982
Of course, machine learning algorithms render this obsolete. You don't have to understand something to program it, just have a vague understanding of how that understanding might come about.
This is our monthly thread for collecting these little gems and pearls of wisdom, rationality-related quotes you've seen recently, or had stored in your quotesfile for ages, and which might be handy to link to in one of our discussions.