人言(未必)信，己言(必筆)記，記作指南針，覓米車不迷。

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.
故明君賢將， 所以動而勝人， 成功出於眾者， 先知也。
Keeping a pen, which is your spear for "Shakespear".