OBSERVATION

low-hanging fruit is when the path to a good is straight, not bent

(Invention / discovery consists of navigating a bent path to a good. The canonical bent path is the graph of the natural logarithm. First-order invention / discovery concerns the part of the path after the bend. Second-order discovery concerns the part of the path before the bend. The invention of the airplane, in the form of a biplane, was a second-order invention, whereas the invention of the monoplane was a first-order invention.)