From The Penguin History Of Latin America, by Edwin Williamson (Penguin, 2003), Kindle pp. 195-197:
The state of Spain was embodied in the weak and imbecilic Charles II, the last of the Habsburg line and a monarch incapable of male issue. Upon his death in 1700 there followed a war among the European powers to decide the Spanish succession. Philip of Anjou, the grandson of Louis XIV of France, eventually acceded to the throne of Spain, but his right to it was recognized by his enemies at the price of important concessions set out in the Treaty of Utrecht of 1713. Flanders and the Italian dominions were lost to Austria and Savoy; Great Britain kept Gibraltar and Minorca, and was allowed the exclusive right to supply African slaves to the Spanish Indies, and to an annual shipload of merchandise for trade with the American colonies; Portugal retained her smuggling centre of Colônia do Sacramento on the east bank of the River Plate. These concessions to Britain and Portugal underscored Spain’s imperial debility, since they infringed, at least for a time, the monopoly of trade with the Indies, which she had done so much to defend. Spain’s sovereignty was now reduced to the Peninsula and her realms in America and the Philippines.
This curtailment of power, though humiliating, at least unburdened Spain of dynastic possessions in Italy and the Low Countries which had drained her over the past two centuries. The Treaty of Utrecht, in fact, forced Spain to relinquish the Habsburg concept of empire, based as it had been on an essentially medieval vision of a supranational constellation of kingdoms under a single sovereign pledged to the defence of Catholic integrity in Europe. The new dynasty of French Bourbons would rule Spain as a European nation state among others, and her still very substantial dominions overseas would be regarded as resources to be exploited economically so as to strengthen her position in the theatre of European power politics. Over the course of the new century, therefore, the Bourbons were to recast the aims and methods of Spanish imperial government.
The spirit of reform significantly altered the ideological basis of the Catholic monarchy, which the Habsburgs, having taken it over from Ferdinand and Isabella, had developed as the guiding principle of their imperial statecraft. The peculiarly Spanish symbiosis of Crown and Church, which endowed the Catholic monarchy with its monopoly of legitimacy, gave way under successive Bourbon kings to a more stringent absolutism of French regalist inspiration. According to this new doctrine of the divine right of kings, the monarch was invested with the authority to rule by God Himself; his power, therefore, was not limited in principle by religious and ethical sanctions upheld by the Church, and much less so by the more ancient, medieval sense of contract with or obligation to his subjects which was still latent in Spain and which had always been much closer to the surface among the conquistadors and their successors in the Indies.
The new regalism permitted the monarch to do what the Habsburgs had been restrained from doing by the force of religious counsel: it allowed the Crown to frame policies on pragmatic grounds of national self-interest. Impracticable chimeras upon which Catholic Spain had spent so much blood and treasure – the defence of orthodoxy against Dutch rebels and English schismatics, the crusade against the Turk, the protection of Indian rights in the New World – no longer needed to be pursued beyond reasonable limits, for the light of reason had to be allowed to filter through the blinds that kept Spain in her neo-medieval ‘darkness’. And yet, those blinds could not be removed altogether; the Catholic Church was too well entrenched in the state and society and, in any case, the Bourbons realized the value of the Church as both a pillar of the social order and a unifying factor in a far-flung empire.
The ideology of the Bourbon reformers has been aptly called the Catholic Enlightenment, for it was a cautious attempt to adjust to the scientific and rationalist spirit of the eighteenth century without disturbing the fundamentals of the Catholic faith.