"The answer was that in Burundi, having a clean bill of health has taken on a very particular meaning: unless and until you have paid for your hospital treatment, you simply can't leave, you are in effect a captive."

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To defer anything to the Greek Calends is to defer it sine die. There were no calends in the Greek months. The Romans used to pay rents, taxes, bills, etc., on the calends, and to defer paying them to the “Greek Calends” was virtually to repudiate them. (See NEVER.)

— E. Cobham Brewer