January 30, 1926
In answer to your question about Sargent's "musicalness" permit me to jot down in a loose way the various impressions I received of this in the course of many years of my enjoying the privileged of his delightful and generous friendship. I met Mr. Sargent some 35 years ago after a Symphony Concert in Boston where I had played Lalo's "Symphonie Espagnole," a delightful work of which Sargent was very fond. [p]
He came to the Artist room that evening and with that irresistible charm of his said a few words which made one rise in one's self esteem and then arranged for our meeting a few days later at dinner in a mutual friends house. On this delightful occasion Sargent played with me "en petit Comite'" the Symphonie Espagnole in which he revealed himself as the admirable musician which he innately was. He was quite amazing in accompanying The 3rd Movement ("Interme'de") a quite splendid piece of music with rather complicated rhythms in 5/8 time, which he played with complete musical and rhythmical understanding, verve and spirit. In his luminously intelligent manner he spoke of various characteristics of Spanish rhythms in music, quite in the manner in which M. Fdouard Lalo had expounded these intricacies to me in prior years. [p]
That same evening we played the first Sonata by Gabriel Fauré  for whose music Sargent had a strong predilection which I ever sincerely shared. Sargent had the insinuating and consummate art of initiation music lovers and musicians as well, to the hidden charms, harmonic innovations and the felicitous melodic lessons (?) in the works of this unassuming composer of genius. [p]
To come back once more to our playing Fauré perplexingly "swift" Sonata, Sargent sailed through his part in those early days. Not by any means that he always played all the notes, but better than that, when cornered by a surprise difficulty, he revealed his genuine talent for music by playing all that which was and is most essential. In other words he was in music as in all things "frightfully" intelligent, not merely glib or clever. [p]
He knew Wagner's scores much more intimately than many musicians and in bygone years played through the better part of them with complete comprehension, deep interest and genuine love for all the beauties in them. He discriminated amazingly well. Of Richard Strauss he said: "He is often discouragingly common place, but he has a virility of saying things which is unusual and convincing, often quite in the grand manner." What he liked in Strauss' work was "the organic power, the structural design. The 'charpente', is there; one feels the lungs, the heart, the liver, all are functioning!" Of Debussy's works he liked best, "The afternoon of a faune," and many of his Piano pieces. Strange to say "Pelias and Melisande" he thought rather "anaemic." On the whole he did not care much for "le precieux" in any art. [p]
His ear was strangely sensitive for unusual harmonic progressions, in fact he had an unusually fine memory for them. I have known him to be haunted by certain ones, after one hearing he would not rest there until he had solved the harmonic riddle. Without the music, he would do this at the Piano by sheer tenacity of oral memory. [p]
His musical training must have been from the start unusually good, for I have heard him solfegise like a musician difficult passage, that he had not played well at first sight reading. His unusually great intelligence helped him in music as in everything else that he ever undertook. In later years S. had somewhat lost his cunning in playing the Piano. This was due no doubt to lack of practice and his failing eyesight, by which I mean that glasses interfered much with his sense of accommodation while playing. [p]
I do not know whether Sargent ever tried himself in musical composition yet there is no doubt in my mind, that had he chosen to become a musician he would have risen to eminence in our art in one way or another.
It is unusual to meet so marvelously endowed a man possessing such simplicity of manner, such goodness of heart, such genuine human kindness in his nature. He had the innate bearing and dignity of a noble man. His life was to my mind the fullest imaginable, for he was ever alert, in his joy over the petal of a flower, over a feather of a small bird, in the mystery of the propelling power of a little snake in the grass. He knew a great deal about natural history. He knew a great deal because he usually remembered everything he had read. He was the most voracious and discriminating reader I have ever met. He belied the French saying "Pour devenir un grand artiste il faut etre, il faut rester fruste." Fruste de connaisances the meant, i.e. not to know too many things, not know too much. He was just a glorious exception as a genius always is, and just could not help being almost omniscient with so exceptional a memory as was his. To have known so great, so lovable, so delightful a man has been one of the greatest privileges of my life. To have appreciated the honor of enjoying also his friendship many explain to you the profound affection in which I hold today his memory.
(Loeffler's letter to Charteris , P147-149)
There are a number of other letters explaining in a wonderful way how John worked with music
French composer Gabriel Fauré was a close personal friend to Sargent.
"Pour devenir un grand artiste il faut ètre, il faut rester fruste." Fruste de connaisances they meant, i.e . . . -- To become a great artist it is necessary be, it is necessary to remain fruste. By fruste they meant, i.e. not to know too many things, not know too much