He's right. The last codebase I worked on that you had a chance to understand was MS-DOS. By the time Windows NT came along, you could be an expert on the scheduler or an expert on the allocator, but you weren't going to know fibers and OLE embeddings at the same level. Plus, I'm wired to remember what code looks like in the editor, so I've got to see it, and you just can't see it all. There's too much code for my context window. And in talking to people on the team much smarter than me, I'm not the only one. Eventually, your brain (or mine, at least) sorts them into specifics and generals. So I might know specifically how fork() works but only have a general sense of how printf() actually formats floats. It still FEELS like you know, but you don't.