Why are there multiple quotation marks in a long quote?

I came across an issue when reading Dr Seuss's How the Grinch Stole Christmas!

(Image via Daily Nutmeg)

And the more the Grinch thought of this Who-Christmas-Sing,
The more the Grinch thought, "I must stop this whole thing!
"Why, for fifty-three years I've put up with it now!
"I MUST stop this Christmas from coming!
                                                                              ... But HOW?"

The writer adds quotation marks to the start of each line in what might be a block quote needing only quote marks once right at the beginning and once at the end.

Can anyone please explain why this is done? Is it a stylistic choice? Or is the writer following some type of rule with the use of punctuation?