During the summer of 1881 Froude received from Carlyle's surviving brother, James, and his surviving sister, Mrs.Austin, a letter dated the 8th of August, and written from Ecclefechan, in which he was implored not to give up his task of writing the Life, and assured of their perfect reliance upon him.
This assurance is the more significant because it was given after the publication of the Reminiscences.

It was renewed on James Carlyle' s part through his son after the appearance of Mrs.
Carlyle's letters in 1883, and by Mrs.Austin through her daughter upon receiving the final volumes of the biography in 1884.

Miss Austin wrote at her mother's request on the 25th of October, 1884, "My uncle at all times placed implicit confidence in you, and that confidence has not, I am sure, in any way been abused.

He always spoke of you as his best and truest friend." Time has amply vindicated Carlyle's opinion, and his discretion in the choice of a biographer.
As Mrs.Alexander Carlyle considered the publication of the memoir, which is by far the most interesting part of the Reminiscences, to be an impropriety, and a breach of faith, it might have been supposed that she would repudiate the idea of deriving any profit from the book.

On the contrary, she attempted to secure the whole, and refused to take a part, declaring that Froude had promised to give her all.