人言(未必)信，己言(必笔)记，记作指南针，觅米车不迷。

At YMCA, I was impressed by a man who kept an exercise record while in training.
A Japanese man took a picture for each meal he was taken, when he had inspiration for invention after the meal, he can trace the content of the meal.
Another Japanese jot down a detailed diary for everything he saw, the table,etc.
Winston Churchil kept three diaries a day, incl. one for art.
故明君贤将， 所以动而胜人， 成功出于众者， 先知也。
Keeping a pen, which is your spear for "Shakespear".