The taxes paid by Castile > the new world gold and silver, by a considerable margin. (according to The Rise and Fall of the Great Powers)
Huh, might need to confer the sources, (i have Rise and Fall on my kindle so that can be don at work, but those number were from The Cambridge Economic History of Europe Vol 4 The Economy of Expanding Europe in the 16th and 17th Centuries & The New Cambridge Modern History,.Vol.04:The Decline of Spain and the Thirty Years War,1609-48\49 and i need to be home to look at those.)
While Rise is a very good book, it does have some flaws (it does not take British financial strength into account when he talks about the WW1 period as an example)
Anyway, the point i was trying to make is that the main resource required to fight in this period is money.