Interesting you should say that. I wrote a comment last night (and then decided not to post it) that went like this:

That's one of those lines, like the opening sentence of Anna Karenina, that is written so authoritatively that you just take it for granted when you read it, but when you stop and think, there's no reason to believe is true.

(The reason I didn't post it is because I don't accept that the quote, even if true, invalidates what I said about naive people getting sucked into the beast. Disputing whether the quote is true makes it seem like I'm conceding that point, which I ain't. I'm the last person to defend the "reasonable man".)

Edit: Shaw was great though. "Animals are my friends and I don't eat my friends" is Wilde-worthy.