I love this quote from George R.R. Martin — 'A reader lives a thousand lives before he dies. The man who never reads lives only one.'
I just learned today of a similar formulation from St. Augustine - 'The world is a book and those who do not travel read only one page'
After many google searches I've been unable to find a quote that more closely matches Martin's but predates it. Confirmation that Martin originated this form would make me equally happy as learning of another earlier phrasing of the quote.
I should make it clear that I am interested in similar meaning as well as similar phrasing. I find that the frequently mentioned quote from Shakespeare's Julius Caesar is almost opposite in meaning: 'Cowards die many times before their deaths; the valiant never taste of death but once.'