My son still believes in Santa Claus. Or at least, at 12, he's hanging on to some shred of that belief, because he must have serious doubts by now. Or maybe he is very elaborately leading me to believe in his belief.

Thus, I either did a very good or a very bad thing on Christmas Eve.

My ex and I bought the same present: Guitar Hero III, a computer game that seems sort of not-so-bad and perhaps even educational in that the player, equipped with a guitar specifically designed for the game, "plays" the notes as the music - represented by flashing lights - unfolds on the screen. It meets the Mommy Test of acceptable computer game, likely because I actually want to play myself.

By the time I discovered my ex had it, it was too late to exchange the game. So, at about midnight on Christmas Eve, having wrapped and situated all the gifts under the tree, stuffed the stocking and tossed into the trash can a cookie or two to give the appearance of a snacking Santa, I sat at my computer and wrote Robby a note.

The note came from Santa, natch, and read - partially - like this:

"Ran into your mother, who as you may know is a bit of an insomniac, this evening here. We had a lovely chat about you, but when I shared with her your wish list, it became clear I had erred and sent you a duplicate gift to your father's home."

I debated adding that since his father lives in bumfuck, it's easiest for him to exchange my gift instead of his dad's, but refrained.

Santa/I instructed Robby in the return of the gift, and that he should get himself another toy or game he wanted instead. He also encouraged Robby to keep up the good work at school, and "Help your mom around the house as much as possible; she appreciates it more than you can imagine."

I debated rephrasing this to say, "Do whatever your lovely mother says. You're 12 now for God's sake, the only man in that big house she bought almost entirely for you -- and I'm still watching." And refrained again.

Instead, I ended it with:

"Know that you are truly among my shining stars."

Signed, "Santa C."

Santa/I then added what I thought was a rather humorous P.S. It touched on a subject Robby had brought up a few weeks ago, about a news story he'd heard that Santas nationwide were being discouraged from saying 'ho-ho-ho,' for fear some women would be offended. "Isn't that ridiculous?" Robby had said.

Santa apparently agreed, as he wrote: "I enjoyed over-hearing your observations about the 'ho-ho-ho' debacle; what a bit of rubbish that was, eh?"

I taped this missive to the Guitar Hero III box and collapsed into bed.

He woke me at about 6:30. "Mom, come read this!"

Still bleary-eyed, I pored over it, feigning great surprise and amusement. "Oh yeah!" I said. "Gosh, I was so tired I barely remember it, but we did meet last night!"

Robby didn't ask any follow-up questions, such as, "What was he wearing? Is he really fat? How did he get in? What did you say about me?" or other such things that should have come naturally. And when the neighbor boy, who is 9 and definitely still a believer, came by to see Robby's gifts, he said "no" to my suggestion that he share the note with his friend.

Yet later, when the neighbor kids had come and gone, I saw him reading it again.

I am left to wonder what this means. I had been quite sure, based on the fact that he wrote separate wish lists for both his father and I, that he had abandoned the whole Santa thing. I had felt certain of it, too, because he grinned at me slyly while we shopped at Christmas Eve and said, "Are you getting things for me?" But I'd been sure mostly because he's 12, living in a modern world, where secrets about everthing from Santa to the birds-and-the-bees are early on disabused.

I was, in fact, relieved by the idea. No more watching my words, staying up til the wee hours to slide presents under the tree, remembering to put "From Santa" on some gifts and "From Mom" on others. No more deception, period.

But the balance beam we parents walk on this issue is so very thin. If we ask our children about their beliefs, we surely cause them to question it in their minds, perhaps even to question us. And almost none of us are really ready to break that magical bubble. On the other hand, we'd rather they learn it from us - the creators of the dream - than some playground friend who feels duty bound to share his newfound knowledge.

Yet he lives in a different world than many children, attending a school of only 25 K-8 students. How many of those 25 still believe? And how many of the rest know not to say anything? Could it be all 25, in one way or another, keep Santa alive? He is also an only child, without siblings to leak information to his ears.

So I say nothing. And wonder.

My son is smart and sensitive, particularly, I think, when it comes to his father and me. He relays to us both almost nothing but necessary information about the other and about his lifestyle in each home, rarely dropping a hint as to which home - if either - he prefers. After at one point telling me he hated his stepmother, he later said everything between them was fine. I do not know the truth of this matter, and do not ask because I believe he will varnish his answer.

So it seems plausible to me he's keeping up the charade not for himself, but for us. Because he believes we enjoy it and that it might hurt us to realize he is growing up, leaving such things behind. Perhaps he read the note so fervently because he realized it was from me, and found it amusing, maybe delighted that I had called him a "shining star."

Years from now, I'll have the answers to these questions. Someday, it will be safe to ask him if he thought Santa really wrote to him.

But for now, I stay quiet. And while part of me bemoans the drudgery of keeping up the ruse, another part of me hopes my son still believes in Santa. That, in a world over-run with bad news and broken hearts, he will always believe; if not precisely in Santa, in this wonderful intangible the jolly old fellow represents. That he believes forever in magic.