"Given, however, a sufficiently eclectic appreciation of the qualities of form and colour which make a work of art, and a nature not to be baffled by a multiplication of difficulties at the outset, this method of study has its advantages. It keeps ever present in the student's mind the final end to be attained, and the incessant use of the brush, with its implied rendition of form and colour by masses and planes which exist before his eyes, rather than by the point and masses of black and white tones which are the necessary conventions of the usual method, gives him a mastery of his tools which is superior and, as I have already repeated, is absolutely logical. Joined to a sincere and stimulating enthusiasm as a teacher, our master showed great perception and consideration for the individual temperament of his pupils; and I have known him to recommend diametrically opposite courses to different men, as he judged might be useful to one or the other."
"As temperament varies in different painters, greater or less stress is laid by them upon qualities of form or colour, and there were men in Duran's who drew well and have since continued to do so, and, despite the heresies of our youthful career in the estimation of academical Paris, few of the ateliers of the time have turned out men of more renown to-day in the various branches of art."
"The atelier was organized on a democratic basis, all students paying a certain amount each month, which went for the expenses of rent, heating, and the hire of models; our master giving gratuitously, in the service of art and in gratitude for similar gratuitous instruction received in his youth, his services two mornings of every week. This was no light sacrifice of the time of a busy portrait-painter and, but little later, the service given was increased by visits to our own studios; when we were preparing pictures for the Salon, when he was ever willing to counsel and help us."
In light of this detailed and articulate description of Carolus-Duran's method and why it was more difficult for the student than the standard academic method, it can help make sense why Sargent, who was naturally apt at working in this particular way, quickly rose to the top of his class. But, as Low pointed out above, Carolus-Duran did have quite a number of outstanding students (although some of them only stayed at Atelier Carolus-Duran for a few months or so before transferring to methods that emphasized drawing more), including Kenyon Cox, Theodore Robinson, James Carroll Beckwith, Jan Stanislawski, Paul Helleu, and Ramon Casas.
(Excerpt fromA Chronicle of Friendshipsby Will H. Low)