Usually, when someone writes a book, they do a 'rough draft' and then go back through it changing, polishing and perfecting the text, until they are happy with the way it is written. Some authors write their entire book several times, making changes and re-writing whole chapters, and even then they may have more work to do if the publisher has some further suggestions.
The same could be said about anything which humans do. It is almost impossible for any human to produce a major work perfect in every detail first time. Music, dance, painting, acrobatics, ice-skating, sport . . . in ever…
