In conclusion, Degas’ portraits of Estelle – both in New Orleans and in Paris – contain characteristics that are quintessentially “Celestine,” as evident through a study of his outlines. As noted by Duranty, a nineteenth century, Degas’
drawing is so individualistic and is such as personal means of expression that we cannot try to derive any method, process, or opinion from it. It intimately unites with the aim and it is an unseparable companion to the idea (qtd Pecírka 21)
For Duranty, when Degas sat in his studio – or in a room far inside his family’s house in New Orleans – and began to paint, he could not control his outlines. These were such impulsive "personal means of expression” that neither the artist nor the audience can derive a straightforward interpretation of them. Although he may not have been aware of it, therefore, Degas’ memory of his 
mother pervaded his depictions of Estelle. Degas’ obsession with capturing his mother in Estelle was such that after returning to France from his sojourn to New Orleans he plastered the top and bottom of Portrait of Mme. René De Gas, sketching new portions to the painting but never finishing them. So haunted was he by the ghost of his mother that he attempted to add on to a portrait that so resembles her at her prime. He was unable to fill in the drawings, distracted, perhaps, but most likely because he did not have Estelle as a model and because no other model – not even his sister (who filled in on many different occasions) – would do. The completion of Estelle’s portraits was a “difficult” (qtd. Mauclair 111) thing, indeed, he never completed the Portrait of Mme. René De Gas, mainly because the true model for his portraits of Estelle - his mother – was long dead.
Images:
Estelle Musson, photograph of a drawing, ca. 1860. Collection of Marie Estelle Moyer (Feigenbaum 128).
Anonymous Miniaturist, Célestine Degas, ca. 1832-34. Location Unknown (Feigenbaum 106).