Description: The scattering of light by light is considered in case where the internal particles of this process have spin zero. The original calculation of this process was performed by Karplus et al. (1950). The pedagogical explanation of this proces was realized for instance by Akhiezer et al. (1965), or, by Beresteteskii et al. (1982). We use here the model with the Green function for the spin zero0 particles. The article is written with the mathematical simplicity and the Schwinger pedagogical clarity.