Comment by man-and-laptop

“Young man, in mathematics you don't understand things. You just get used to them.” -- John Von Neumann

My approach to "understanding" (if that's the right word) the quaternions was to first memorise the various identities relating quaternion algebra to 3d rotations. I didn't actually "understand" them, and I still feel a bit dodgy with them, but I got used to them in a way. Second, it helps to try and solve some problems with them. That also gets you "used" to them.

The 3B1B videos are supplementary for me. I still find quaternions a bit miraculous. And Geometric Algebra doesn't seem like the solution for me, because it's another weird and even more complex formalism.