"It's the economist in me, Michael. :-) Wealth *is* productive power. Because our main wealth is us. Or, as Marx put it in Grundrisse, our real wealth is the "developed productive power of all individuals," and -- quoting approvingly an anonymous pamphlet -- our true wealth is a short workday, our free or disposable time."
Or, as Yeats put it,
Toil and grow rich , What's that but to lie With a foul witch , And after, drained dry, To be brought to the chamber Of one long sought with desire.
J.