"Do make him play for you," Sargent wrote of Delafosse in a letter to Isabella Stewart Gardner, his dearest friend in Boston and a great patroness of the arts. "I am sure you will have the greatest pleasure in his wonderful talent, both as a composer and a virtuoso." "He is the only man who has taken the trouble to study certain difficult and beautiful piano compositions by [Gabriel] Fauré," Sargent explained to Mrs. Gardner on another occasion. This was perhaps the true source of the painter's affection for Delafosse, for Sargent loved Fauré's sprightly piano impressions. Sargent was a gifted pianist himself. According to composer Percy Grainger, "To hear Sargent play the piano was a treat, for his pianism had the manliness and richness of his painting. . . . He delighted especially in playing his favorite, Fauré." But Grainger also tells us that Sargent's paternalistic support of young musicians was perhaps his greatest contribution to music: "Music seemed to be less a recreation to him than a sacred duty, the duty of aiding especial musical talent wherever he found it." Sargent, Grainger tells us, "had been the apostle of Gabriel Fauré in England, bringing over that great composer to London for public and private performances of his compositions, arranging performances of Fauré's work by the Cappe Quartet, Léon Delafosse, and other exquisite artists and the like."

Of course Delafosse is a decadent especially in the matter of neck-ties-but he is a very intelligent little Frenchman, and a composer and excellent pianist, who is probably going over to America in a year's time, so I sent his portrait over as a forerunner.

—John Singer Sargent, to Isabella Stewart Gardner, on Léon Delafosse, 1899

Sargent, in a letter to Isabella Stewart Gardiner, revealed something of his purpose in painting the young Léon Delafosse. The charming young pianist—he had won first prize at the Paris Conservatory of Music when only thirteen—was known for his delicate beauty. Nicknamed "the Angel," Delafosse must have been a captivating portrait subject by his physical characteristics alone. But Sargent was equally charmed by Delafosse's musical ability—particularly his mastery of the modern piano pieces of Sargent's favorite composer, the Frenchman Gabriel Fauré (1845-1924). At a time when live performance offered the only opportunity for one to hear music, Delafosse was a favorite attraction at the private salons of the most elite patrons of music in both Paris and London. Sargent was eager to introduce Delafosse to his American friends, and he sent this portrait for public exhibition in Boston in advance of the pianist's planned concert tour to American cities. The painter did so to do his part to garner attention for this young man of extraordinary talent—note the stress that Sargent has placed on his subject's long pianist's fingers.