The persistent opposition experienced by rationalist reformers of the Siglo de las Luces (Century of Enlightenment) is most easily, and all too readily, judged by posterity to be a result merely of blind ignorance and prejudice. Had this been true, the reformers' task would have been much easier than it was. Irrational ignorance and prejudice certainly were factors with which ilustristas, and ilustrados – that is, modern rationalists in mere spirit or in practical fact – together with enlightened thinkers of any other century, had to reckon. In 1751, the medical scientist José Ortega, who had been asked to nominate the most reputable Botanist for the Real Sitio de San Fernando, warned against national or individual pride and prejudice in making scientific appointments:

But areas in which ilustrismo strove with far greater difficulty were intellectual areas of reasonable distrust – reasonable, that is, for the period and in the national circumstances.