When he was young, he was student of Felice Del Santo and Antonio Discovolo.
During World War I, Caselli was captured and interned in a concentration camp in Austria.
After that, he studied at the Academy of Fine Arts in Florence, at the "free school of the nude".
His painting style is situated between the first divisionists expressions of the early twentieth century, and a personal expressionism, close to the Austrian groundbreaking movements, but also influenced by the poetry of his friend Viani, with his entire repertoire of characters suffering and desperate.
With aeropittura ("aeropainting") works, technique derived from futurism, Caselli participated in 1933 in the Premio del Golfo (Gulf Award), organized by Filippo Tommaso Marinetti.