Edwin Austin Abbey
Abbey letter to Boston
"I wonder how John is getting on, and whether you have built him a beautiful model yet . I went into his studio a day or two before I sailed and saw stacks of sketches of nude people, saints, I dare say, most of them, although from my curious observations of them they seemed a bit earthy. You will surely get a great thing from him. He can do anything [emphases added by Abbey], and don't know himself what he can do. He is latent with all manner of possibilities and the Boston people need not be afraid that he will be eccentric of impressionistic, or anything that is not perfectly serious and non-experimental when it comes of work of this kind."1) The "beautiful model" refers to a model of the building that Sargent would use to help compose the composition, size, and relationship of his murals within the hall's space. Remember, Sargent would be working from plans only back in England at this point.
(Letter from Abbey to Boston -- possibly Charles F. McKim, archetect; E.V. Lucas, "Edwin Astin Abbey," i.,p.231; quoated in Charteris, p. 108). Charteris doesn't date the letter but I assume it's shortly after he stated work on the first installation which would be sometime after 1890.