About this passageTwo lines, and the shortest chapter in the handbook. It follows directly from the school's division of things into what is in our power and what is not: if events are outside that power, then a wish aimed at them is a wish aimed at something that cannot hear it. What the chapter recommends is a redirection of wanting, not an abandonment of it.
Demand not that events should happen as you wish; but wish them to happen as they do happen, and you will go on well.
In plainer words
Stop insisting that things go the way you want. Want them to go the way they actually go, and your life will run smoothly. This is either the most useful sentence in the book or the most infuriating one, depending on the day, and the tradition is aware of that.
A restatement in modern English, written for this collection. The passage above is the text; this is one way of putting it.