Some years ago I passed many laborious months in archives and libraries at home and abroad, searching and transcribing contemporary papers for what I hoped to make a complete history of the long reign of Philip IV., during which the final seal of decline was stamped indelibly upon the proud Spanish empire handed down by the great Charles V. to his descendants. I had dreamed of writing a book which should not only be a social review of the period signalised by the triumph of French over Spanish influence in the civilisation of Europe, but also a political history of the wane and final disappearance of the prodigious national imposture that had enabled Spain, aided by the rivalries between other nations, to dominate the world for a century by moral force unsupported by any proportionate material power.