From LHSA, here's a short but interesting read about Leica M lenses and the optical engineering virtuosos who have designed them over the decades.
With tomorrow's coming announcement of the APO 35mm Summicron M, the world of photography is about to receive the next installment in this ongoing demonstration of (near) perfection.
Why are Leica Lenses The Best in the World?
The answer lies at the nexus of objective science, an enduring passion for excellence, and a lineage of inspired optical designers steeped in a great tradition
https://lhsa.org/2018/08/why-are-leica-lenses-the-best-in-the-world/