It sounds a lot like circular logic. How do you work out whether someone is smart or not? By whether you see them struggle? I can only ask "how the hell?"

It sounds a lot like circular logic. How do you work out whether someone is smart or not? By whether you see them struggle? I can only ask "how the hell?" And they would say something like, "oh, it's just this and that." That could be someone who, once they understand something, can explain it easily. That doesn't (necessarily) mean that they reached the initial understanding easily.