Outside of a dog, a book is a ...

Outside of a dog, a book is a man\'s best friend. Inside of a dog it\'s too dark to read.
Outside of a dog, a book is a man's best friend. Inside of a dog it's too dark to read.
 Groucho Marx

More phrases

If one does not know to which port one is sailing, no wind is favorable.
What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.
We are masters of the unsaid words, but slaves of those we let slip out.
I have always found that mercy bears richer fruits than strict justice.
A lie gets halfway around the world before the truth has a chance to get its pants on.

Quotes from the same author

Only one man in a thousand is a leader of men -- the other 999 follow women.
 Groucho Marx
My mother loved children - she would have given anything if I had been one.
 Groucho Marx
[He] may talk like an idiot, and look like an idiot, but don't let that fool you: he really is an idiot.
 Groucho Marx
I married your mother because I wanted children, imagine my disappointment when you came along.
 Groucho Marx
I've met a lot of pin-up girls, but I've never been able to pin one down
 Groucho Marx