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The $23 Million Book That Explains Maxima and Minima
A wine merchant with a measuring stick started all of this in 1615. Here is what he accidentally proved about every estimate you will ever make.
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The wine merchant had a stick.
That was the whole method. He pushed a wooden rod in through the hole in the side of the barrel, angled it up to the far corner of the lid, pulled it out wet, read off how far the wine had reached, and charged for that. One number. One price. Next customer.
Johannes Kepler bought wine this way in Linz and could not let it go. A tall thin barrel and a short fat one can swallow the same length of rod and hold completely different amounts of wine. He said so, out loud, in a shop. The merchant presumably kept serving people.
So Kepler went home, did the arithmetic, and in 1615 published an entire book about the volume of barrels.
Then he found something that bothered him more than the merchant had. Near the best possible barrel shape, the amount of wine barely changes at all. Get the proportions noticeably wrong and you still get almost everything. That one observation is the reason every number a statistician reports comes…
