Biblioteca Nacional de España — Madrid, Community of Madrid, Spain

These were sold as a set of eighty, in an ordinary shop rather than anywhere grand, and pulled off sale after a couple of weeks — the usual explanation is that he got nervous about the Inquisition. This one was meant to open the second half, and there's a note attributed to him saying the idea is that reason and imagination go wrong without each other. Whether that's the whole story, I couldn't tell you.

This is apparently a working sketch — Velázquez roughing out how a soldier's back and stance might sit before he committed anything to canvas for a much bigger scene.