Confiscation of personal possessions because you don't have a receipt that proves that you own them is simply arbitrary theft by the government. I don't have a receipt for all my old coins, just as I don't have a receipt for my old books, or for my shirts or for my basket of vegetables.
Still, the state (in most countries) cannot confiscate these things unless they can prove someone else owns them, or that unusually suspicious circumstances apply (e.g, I was stopped whilst running away from a crime scene). I have no obligation do anything to show my
Roman coins belong to me. I don't need to keep receipts or anything. I know that I bought them all legally and no-one else has a claim to them. That's all.
http://en.wikipedia.org/wiki/Possession_(law)
In common law countries, possession is itself a property right. Absent evidence to the contrary, it provides evidence of ownership. Possession of a thing for long enough can become ownership.but it seems not in
Italy.
Back to the Kouros (or to a coin
collection in
Italy): in most countries, the government needs to bring evidence before they can confiscate things e.g. "here is evidence that the Kouros came from tomb X or was stolen from
collection Y". Lacking such proof, the assumption should be that it's owned legally by the possessor. Perhaps it was excavated in 1420 and passed, by sale and family inheritance, to the present owner. Perhaps it was exported from ancient
Italy to decorate a house in Tyre since 400 AD, and bought there by Marco Polo on
his return from
China. Who knows. The current owner doesn't have to have a receipt. It should be enough for him to say "I've owned it since
xxx and got it from yyy" and the obligation is on the government to prove he did not.
Anyway, my coins are my own. Forever. They belong to me. I bought them properly (incidentally almost none from
Italy), I own them, and I'm keeping them.