Recently I was thinking about the Empress Josephine's ring. Her husband Napoleon, Emperor of Europe, gave her a ring made of a wondrous metal, rare and precious, fit for an Empress:
Since then electrochemists have figured out how to extract aluminum cheaply by the ton. We use it for baseball bats, patio chairs, airplanes, and soda cans. Aluminum is no longer a precious metal, but it is now a very useful metal. This is a gain, except from the Empress's point of view. Now she - or her wannabes - must retreat to other metals, until those become cheap to make, and then she must retreat again.
This reminds me of the God of the Gaps. Every time science comes up with an explanation for some natural wonder - the rainbow, say - then those who would explain everything in terms of God must retreat. Their "God of the Gaps" must hide within some gap in the explanation; but since science tends to fill in its explanatory gaps, the God of the Gaps must constantly retreat.
Both Empress and Gap-God must retreat before advancing understanding. How curious a weakness! And how revealing a similarity!