IT WAS AN invitation no book reviewer could refuse. Several weeks ago, well in advance of the pre-Christmas turmoil, I and a dozen other regular reviewers of fiction for Book World received an invitation to participate in a holiday symposium on this tantalizing question: "Which character in fiction would you most like to be, and why?"

Not in the least surprisingly, none of those offered the chance to participate in this novel seminar declined to do so. For some, as you can see from the pieces below, the choice was easy; for others it was difficult, torn as they were among a number of characters who had managed to work their way into their hearts.

IF I COULD be any character in any book (excluding the Holy Scriptures out of reverence, one assumes), I would choose to be Edward Bear, alias Winnie-the- Pooh. The genial bear was chosen after much soul- searching, narrowly beating out Moby Dick and James Bond, for several reasons.

Above all, he is cuddly -- an argument that needs no further elaboration or justification; it is an absolute quality and absolutely to be sought.

A corollary of his physical cuddliness -- a sort of mental cuddliness, if you will -- is his extraordinary equanimity. Pooh suffers many mishaps including long falls into gorse bushes, floods, chronic hunger and scary, ambivalent encounters with such daunting creatures as bees, woozles and heffalumps. He is often uncomfortable, sometimes more than a bit anxious, but he never loses the optimism that makes him a perfect dialectical counterbalance to Eeyore, the eternal prophet of doom.

Pooh is a severely limited creature, to be sure. We all are, but he is aware of his limitations and accepts them, cheerfully proclaiming himself A Bear of Very Little Brain and faithfully acting out that role. Since he fulfills a role, he is surrounded by a supportive peer group who accept him without question on his own terms. And when he departs from the role -- when, for example, he perceives that an overturned umbrella can serve as a rescue boat for a flood- stranded Piglet -- the reaction is inevitably one of surprised delight. It is a pleasant thing indeed to be one of whom little is expected.

Finally, Pooh is, on the whole, lucky. He is lucky, I suspect, precisely because he is so attuned to his own nature and his environment. Piglet sums it up nicely: "Pooh hasn't much Brain, but he never comes to any harm. He does silly things and they turn out right." Given a choice between Brain and luck, anyone who chooses Brain should have his head examined.