The distinction at first attempted between the mysticism that was praiseworthy and that which was dangerous was complicated by the recognized fact that, while visions and revelations and ecstasies might be special favors from God, they might also be the work of demons, and there was no test that could be applied to differentiate them. The Church was in the unfortunate position of being committed to the belief in special manifestations of supernatural power, while it was confessedly unable to determine whether they came from heaven or from hell. This had long been recognized as one of the most treacherous pitfalls in the perilous paths of illumination and union with God. As early as the twelfth century, Richard of St. Victor warns his disciples to beware of it, and Aquinas points out that trances may come from God, from the demon or from bodily affections.[16] John Gerson wrote a special tractate in which he endeavored to frame diagnostic rules.[17] The Blessed Juan de Avila emphatically admonishes the devout to beware of such deceptions, but he fails to guide them in discriminating between demonic illusions and the effects of divine grace.[18] Arbiol describes the uncertainty as to the sources of these manifestations as the greatest danger besetting the path of perfection, causing the ruin of innumerable souls.[19] When, in the eighteenth century, mysticism had become discredited, Dr. Amort argues that, even if a revelation is from God, there can be no certainty that it is not falsified by the operation of the fancy or the work of the demon.[20] When to this we add the facility of imposture, by which a livelihood could be gained from the contributions of the credulous, we can appreciate the difficulty of the task assumed by the Inquisition, in a land swarming with hysterics of both sexes, to restrain the extravagance of the devout and to punish the frauds of impostors, without interfering with the ways of God in guiding his saints. It is merely another instance of the failure of humanity in its efforts to interpret the Infinite.