Time Traveller's Cheques, and Why Is Labor So Expensive?

Over on rasfw, David Tate started the thread "Time Travelers strictly barter", on what would be good for a time traveller to carry with them to get by in their destination. He was particularly interested in things besides the old standbys, silver and gold, things such as spices, synthetic gems, pins, lodestones. But the topic hit upon a couple of past interests of mine: prices in medieval Europe (for the Ars Magica game), and why and how there's such a huge wage differential between the First and Third Worlds.

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