what does means this sentence?

China
September 11, 2010 10:28am CST
I am a chinese,i am reading an english book recently,there is a sentence "outside of a dog a book is a man's best friend,inside a dog it is too dark to read."i don't know what does its mean,whom can explian it for me? thank you very much?
2 responses
@Catana (735)
• United States
11 Sep 10
In English, "outside of" can means "besides" or "as well as" or "also." So a different way to express it might be "A dog is man's best friend, but so is a book." Or, "Besides a dog, a book is a man's best friend." Inside isn't always the opposite of outside. In this quote, the different meaning is being used, making a joke.
• China
13 Sep 10
one thousand thank you!
• India
11 Sep 10
It is just a funny saying. Dogs are mand best friends and books can be the next best friends after a dog. And the funny part is that no one can enter inside and dog and read a book. So it is just a funny quote.
• China
13 Sep 10
thanks a lot!