|French Morocco CB42 & C4|
Joseph de la Nézière was a French painter and orientalist who lived from 1873 to 1944. Detailed information about his life is scarce, but I found some basic info here, even a small photograph. Nézière designed many beautiful stamps for the French Colonies.
On March 8, 1952, Morocco, under French rule, decided to honor Nézière with a stamp on stamp design based on his air mail stamps of 1922. March 8 was evidently a day the French at that time had declared to be their official "Stamp Day". (The annual international "Post Day", later called "Stamp Day", came later, initiated by the UPU - the Universal Postal Union - in 1969). The 1952 issue also marked the 30 years anniversary of the first air mail stamps from French Morocco. The 1922 issue can be hard to find. It belongs to a set of 11 different colors, all with the same "biplane over Casablanca" design.
On another website I found this beautiful poster by Nézière.