Art grandly mirrored reality last night at the National Portrait Gallery.

"American Portraiture in the Grand Manner: 1720-1920" went on display yesterday, and by day's end at least 200 walking portraits of Washington's pomp and power were dancing and dining in the stately elegance of the gallery's ornate halls.

Included in the collection are 73 graceful paintings of ladies in silk and pearls, and gentlemen in dark suits posed with swords and flags. Truth and fiction became indiscernible as taffetas rustled and the clicking of patent leather dinner shoes, many with little bows, echoed in marble halls.

Portrait I:

Abe Fortas standing in front of "The Skater": "Look at the way he's standing," said the former associate justice of the Supreme Court. "He looks so in control with his arms folded so powerfully. He looks a little like me, too."

Portrait II:

Chairman of the Council of Economic Advisers Murray Weidenbaum, in front of "Samuel Chester Reid": "I like the cleft in his chin," said his wife, Phyllis. "He sort of looks like Murray when he was thinner. Murray has a cleft in his chin."

Portrait III:

SEC Commissioner Barbara Thomas, in front of "Mrs. Henry White": "She doesn't look like an SEC commissioner," said Thomas, "but I'm adopting her as one of my ancestors. She radiates intelligence."

Portrait IV:

President of the Board of the National Theatre Maurice Tobin, in front of "Mrs. R.H. Winslow": "Why would anyone want to memorialize her?" asked Tobin. "Look how big her hands are."

The evening began about 9 on the ground floor of the gallery, where guests oohed and aahed over the exhibit. The next stop was floor two. Large strawberries, blackberries, expensive champagne and chocolate were the main attraction there. In fact, only about half made it to the top floor, where there was dancing.

The Weidenbaums, for instance, passed the dancing. "Are you kidding," said Phyllis Weindenbaum. "I danced at my wedding. That was enough."