Except its like both, and unlike both, and like and unlike many things. Sui generis.<p>I don't need to think about what my brain is like to figure out how to use it. My brain is the only thing in the world I really know how to use at all. The feeling guides the use.<p>If I feel like I'm forgetting lots of important things, that feeling is what should guide my intention to write things down. Not some weird metaphor like, I thought I was a database, but really I'm a cache.<p>Imagine someone saying, "I'm gained weight because I thought I was a garbage disposal, but now I realize I'm a community garden." This is wrongthink.<p>I mean, a cache is a database, so the metaphor isn't even useful.