You might call them postcards from the ledge.

Artist Nick Agid carves messages into slabs of stone and mails them to politicians, celebrities, world leaders, authors and fellow artisans.Using material left over from his sculpture work, Agid has lovingly etched more than 600 mineral missives out of onyx, marble and granite.

"It started out being a whim, and it became a serious art project," he says.

He spends about an hour chiseling a message into each stone, always including a request for a reply.

The cost of mailing the four- to five-pound cards is heavy - up to $10 a throw, and much more for international celebrities. But Agid doesn't mind.

"The responses were so humorous, it became kind of addicting to check the mail and see who wrote me back," he said. "I got a letter from the pope and Ted Kennedy on the same day."

Many who have gotten the rock cards - including President Bush, Elizabeth Taylor, director Mel Brooks, author Ray Bradbury and actor Vincent Price - have responded.

Price sent his response on the inner sole of a shoe, writing, "Upon my sole, I've never had such a heavy fan letter. Are you sure you have all your marbles?"

From others - Iraq's Saddam Hussein, for instance - there has been stony silence.

Rep. Dana Rohrabacher, R-Los Angeles, known for his opposition to the National Endowment for the Arts, cast stones at Agid's artistic endeavor.

"The only true value something like your brick has is that which people will voluntarily pay for it," he said. "That's why so many no-talent artists end up seeking grants from the NEA."

San Francisco Examiner columnist Rob Morse took the Postal Service to task for the way it handled his five-pound slab of onyx.

"I still have the rock," he wrote in his column. "It arrived in a plastic envelope and says `Damaged in Shipment.'

"Only the post office could damage a rock."

Relations between Agid and the Postal Service are indeed a bit rocky. Postal workers tend to balk when he shows up with as many as 40 stone slabs to mail.

"We were never mad at him," said Betty Baker, a clerk at the Torrance Post Office. "It's just we avoid him. It takes so much time to mail his rocks. It gets our counters real dirty."

At one point, the Postal Service threatened to stop accepting Agid's mailings. Word was that one of his rocks broke a conveyor belt.

To smooth things over, he sent a carved card to Postmaster General Anthony Frank, who wrote back, "It is always a pleasure to be contacted by one of our customers, especially one as rock-solid as you are."