Mason Gaffney's statement regarding the quotidian nature of much obsolence brings to mind the distinction Arnold Harberger made in his AEA presidential address on a Vision of the Growth Process and published in the AER circa 1998 on whether productivity advance is better envisioned as analagous to yeast or mushrooms. Harberger seemed to favor the mushroom analogy which he also labelled real cost reductions. Offhand, what Harberger had in mind by real cost reductions seems similar to what Mason Gaffney describes; however, I would want to go back and re-read Harberger's article not to mention Schumpeter before pushing this very far. On the other side of the ledger is probably the recent literature on General Purpose Technologies. David Mitch