I've seen the quote "Everything in moderation, including moderation"
attributed to Mark Twain, Oscar Wilde and Horace Porter...did Twain
say it?

I've also seen this one attributed to Twain:

As an example to others, and not that I care for moderation myself, it
has always been my rule never to smoke when asleep, and never to
refrain from smoking when awake.
Read more at http://www.brainyquote.com/quotes/keywords/moderation.html#IpcwxLOwP3HIC6Zj.99

Ellen Komp
Continually Curious