From the Trivia Files: Contest Rules and Another Question

I started this series thinking that I'd post one a week, just like I did with the last series.  However, if I'm going to make this one a competition with a prize, I don't think I should keep my readers waiting long.

Therefore, I've decided to keep the posts coming regularly for the next week.  Before I go any further, I think I ought to lay out a list of rules for this contest.

Contest Rules:

1. Entrants must post an answer to every question in order to be eligible to win.  One answer per question, please.
2. Anonymous answers cannot win prizes, because I won't be able to identify a person to mail the prize to.
3. The prize is a book, So What's the Difference? by Fritz Ridenour.  This is not a paid endorsement, it's just a book I would personally recommend to my readers.
4. All correct answers to the questions will be posted at the end of this series (a really good reason not to keep everyone hanging for months).
5. The winner will be either the person who answers the most questions correctly, or, if there is a tie, the person randomly selected from the list of top competitors.  At the end of the contest, I will announce the winner and ask that he or she email me at the address I will make available so I can know where to send the prize.

So here's the question for today (I'll continue posting over the weekend).  To latecomers: Don't forget to post an answer to the last trivia question, here.

"For as I walked around and looked carefully at your objects of worship, I even found an altar with this inscription: TO AN UNKNOWN GOD. Now what you worship as something unknown I am going to proclaim to you."    

                                                    ...Who said it?