"Worthless"

While cleaning I found something I had feared I had lost: a pair of 100-peso notes from the Japanese occupation of the Philippines during World War II. Now here is evidence that the value of an object is tied purely to mutual agreement among buyers and sellers. A 100-dollar bill from the 1940s would still be worth at least 100 dollars today -- probably more due to desirability to collectors.

In contrast, an eBay search of completed items suggests that my bills are only worth a couple of American dollars now. But I think I would like to hold on to them because I like having tangible evidence that the Occupation did happen, and a reminder that war can radically alter what we believe is valuable and what is not.