Landau and Feyman diagrams

Landau considered the Feynman diagrams and the Dyson concept of their visual summation as a breakthrough in the physics of particles. This visual perception in his opinion activated the person intuition. In this intuitive way Landau introduced the concept of partial summation which led to major results in the particle physics and the condensed matter theory. Some of his and of the members of his school results will be presented in a pure visual way.