Original sentence: The expression refers to a popular story of how Columbus, having been told that discovering the Americas was no great accomplishment, challenged his critics to make an egg stand on its tip; and, after they gave up, he did it himself by tapping the egg on the table so as to flatten its tip
Edited sentence: The expression refers to a popular story of how Christopher Columbus, having been told that discovering the Americas was no great accomplishment, challenged his critics to make an egg stand on its tip; and, after they gave up, he did it himself by tapping the egg on the table so as to flatten its tip