"That which we persist in doing becomes easier to do; not that the nature of the thing has changed, but that our power to do has increased."
He had learned that quote, along with many, many others, (some of them a page or more long), from off the back of our toilet door while he was growing up. If you get all of our family together and prompt them with a word or two, I think that most of our children still remember all kinds of quotes, word for word, that they learned in that way.
I used to change the quotes fairly regularly. Sometimes they were scriptures, sometimes even maths or physics equations that one of the children was trying to learn before a big exam. If I thought anyone needed advice or encouragement in any particular area, there was often a quote about that on the back of the door.
It would sometimes shock me to realize how much they had memorized - especially some of our teenage boys that didn't even like to read! Amazing what can be accomplished with a captive audience! :)