What is the "geometry" illustration given by Lewis?

Teachers will tell you that the laziest boy in the class is the one who works hardest in the end. They mean this. If you give two boys, say, a proposition in geometry to do, the one who is prepared to take trouble will try to understand it. The lazy boy will try to learn it by heart because, for the moment, that needs less effort. But six months later, when they are preparing for an exam, that lazy boy is doing hours and hours of miserable drudgery over things the other boy understands, and positively enjoys, in a few minutes. Laziness means more work in the long run. Or look at it this way. In a battle, or in mountain climbing, there is often one thing which it takes a lot of pluck to do; but it is also, in the long run, the safest thing to do. If you funk it, you will find yourself, hours later, in far worse danger. The cowardly thing is also the most dangerous thing. Check this out at the link below: