What is this supposed to do? (meme thing)

I've seen this one before, didn't do it. Just now got it from doco:

1. Grab the nearest book.
2. Open the book to page 23.
3. Find the fifth sentence.
4. Post the text of the sentence in your journal...along with these instructions.

But first you should understand the underlying structure and how it is affected by movement.
--from Draw Horses with Sam Savitt