 However, it was impossible to change the entire laws of both realms by force alone, and due to reasonable suspicion of one another the monarchs kept their kingdoms separate during their lifetimes.The only way to unify both kingdoms and ensure that Isabella, Ferdinand, and their descendants maintained the power of both kingdoms without uniting them in life was to find, or create, an executive, legislative and judicial arm directly under the Crown empowered to act in both kingdoms.This goal, the hypothesis goes, might have given birth to the Spanish Inquisition.