Diego Rivera’s cubist period came to an end in 1918. His name would remain linked to the legendary group of young artists that founded the school of Paris. In The Mathematician, a portrait of his friend Dr. Renato Parescat, Rivera abandons the decomposition of forms and returns to his old interest in the reflection of light and more naturalistic representation. Although this work is highly structured, with the proportions and disproportions in the lengthening of the figure rigorously calculated by the artist, it represents a condensation of everything he learned about form, light, color, and plasticity in painting during his European years. Executed in 1919, The Mathematician not only constitutes one of the centerpieces of the collection of the Dolores Olmedo Museum but was also considered by the artist himself one of his most important works, as attested in a letter he sent to Dolores Olmedo recommending the purchase of several of his paintings.