According to Noble David Cook, a community of scholars has recently, albeit slowly, "been quietly accumulating piece by piece data on early epidemics in the Americas and their relation to the subjugation of native peoples." They now believe that widespread epidemic disease, to which the natives had no prior exposure or resistance, was the primary cause of the massive population decline of the Native Americans. Earlier explanations for the population decline of the American natives include the European immigrants' accounts of the brutal practices of the Spanish conquistadores, as recorded by the Spaniards themselves. This was applied through the encomienda, which was a system ostensibly set up to protect people from warring tribes as well as to teach them the Spanish language and the Catholic religion, but in practice was tantamount to serfdom and slavery. The most notable account was that of the Dominican friar Bartolomé de las Casas, whose writings vividly depict Spanish atrocities committed in particular against the Taínos. It took five years for the Taíno rebellion to be quelled by both the "Real Audiencia"—through diplomatic sabotage, and through the Indian auxiliaries fighting with the Spanish. After Emperor Charles V personally eradicated the notion of the encomienda system as a use for slave labour, there were not enough Spanish to have caused such a large population decline. The second European explanation was a perceived divine approval, in which God removed the natives as part of His "divine plan" to make way for a new Christian civilization. Many Native Americans viewed their troubles in terms of religious or supernatural causes within their own belief systems.