[steppi]

In undergrad I took a graduate class out of Calculus of Variations by Gelfand and Fomin [0] that went deep into the math of classical mechanics but assumed students already knew the relevant physics. I hadn't taken a proper classical mechanics class, and working through Volume 1 of Livshitz-Landau in parallel with the lectures helped to ground the material for me. A brilliant classmate who’s now a successful mathematical physicist had recommended the series.

Later I tried to learn Quantum Mechanics while taking a course on Operator Theory, but gave up on using Volume 3 of Livshitz-Landau because it was just too impenetrable. I ended up going with Sakurai instead.

I found Volume 1 to be beautiful read and felt like I was learning something profound. Volume 3 was beyond me. The only thing I'd say these books have in common with the Feynman Lectures is a dearth of exercises. This wasn't an issue for me reading Volume 1 of LL because that Calculus of Variations course had many exercises which I just wasn't in a position to appreciate without knowing more Physics.