Home » Outside of a dog a book is mans best friend. Inside of a dog its too dark to read. ~ Groucho Marx Quotes Outside of a dog a book is mans best friend. Inside of a dog its too dark to read. ~ Groucho Marx Outside of a dog, a book is man’s best friend. Inside of a dog, its too dark to read. ~ Groucho Marx by Johnny Stones, for Truth Inside Of You. Don’t forget to visit our Quotes Gallery! November 26, 2015