Amazing lectures by Paul Dirac in 1975. Worth checking out.

 Fascinating and lucid lectures by Dirac that give deep and mostly accessible insights into development of QM from early days in the 1920s right thru many decades. He’s a very good lecturer! 

https://youtube.com/@el3ktropionir

These 4 lectures are an incredible history of physics account by Dirac who was there in the thick of it and won a Nobel Prize in Physics in 1933 along with Schrödinger.