This proof was worked out in the framework of Microlocal Analysis which is based on the idea of quantization, and the most useful quantization method was also suggested by H.Weyl (1927):
In the second part of the talk I will discuss quantization, uncertainty principle, quantum and classical dynamics.
In the third part of the talk I discuss the proof: main singularity, the role of periodic trajectories in the remainder estimate and their possible contribution to the main part