Samuel Johnson, 1709-1784, citing a college tutor
Yet I do think Johnson, or his tutor, had a point. When I was working as a newspaper copy editor, I had to make stories fit into the available space. That often meant cutting out everything that wasn't absolutely necessary. On many occasions there would be one passage in the story that I thought was particularly fine. It might be a good metaphor, an excellent quote or just a nifty bit of description. More often than not, it seemed, that line or two had to go. It may have been fine writing, but it wasn't as necessary to the story as all the other lines.
Making this cut was especially galling when it was my own writing that I was trying to squeeze into the space.
Johnson was probably thinking of something else, however. This came to me while I was reading Stacy Horn's Imperfect Harmony, a book I hope to have more to say about within a few days. Writing about her own experience as an amateur composer, she says "there is the temptation to try to make your music too clever, coming up with all sorts of neat contrapuntal techniques, at the expense of what sounds musical (and what is fun and reasonable to sing!)."
What's true of composers is probably also true for other creative people. Have you noticed how many singers like to show off a little bit on the last line of the national anthem? Dancers may be tempted to throw in an extra fancy move and painters a little extra flourish to their work. Writers, too, sometimes like to show off. Some of those long, descriptive passages one often finds in novels are just writers showing off. Striking out such passages might, in many cases, improve the novel.
Reading over one's own compositions, it may be wise to remember Samuel Johnson's advice, and when you find a passage you are particularly fond of, ask yourself if it actually improves your work or if it is just showing off.