Suppose you don’t know the geography of the earth at all, you send out expedition fleets time and time again, and these fleets discover new continents one after another. Until the number of known continents increased to six. But you don’t know if this is all the continents on the earth. You continue to send out your fleet, and you have set off hundreds of times, but they haven’t discovered any new continents. At this time you come up with a conjecture: there are no more continents on the earth.
This conjecture seems reasonable, but it still needs to be demonstrated. At this time, Perelman appeared, and he proved to you and the world in a perfect and rigorous way that there are indeed no more continents on earth.