I'm not a native English speaker and cannot get the full meaning of this part of Orison Swett Marden's self help book "Pushing to the front":
"How hard I worked at that tremendous shorthand, and all improvement appertaining to it," said Dickens. "I will only add to what I have already written of my perseverance at this time of my life, and of a patient and continuous energy which then began to be matured."
It is in the chapter 23 which is entitled "The reward of persistence".