"Many other instances might be mentioned testifying to the remarkable extent to which psycho-therapy, in one form or another, was utilized in the countries of the ancient world. This, of course, does not necessarily imply that the ancients had any real understanding of the psychological and physiological principles governing its operation. On the contrary, there is every reason to believe that they used it much as do too many of the mental healers of to-day--on the basis of 'faith cure' pure and simple, with no attempt at diagnosis, and in a hit-or-miss fashion. It was not until the very end of the Middle Ages, so far as history informs us, that anything even remotely resembling a scientific inquiry into its nature and possibilities was undertaken, and then only in a faint, vague, indefinite way, by men who were metaphysicians and mystics rather than scientists. The first of these, Petrys Pomponatius, a sixteenth-century philosopher, sought to prove that disease was curable without drugs, by means of the 'magnetism' existing in certain specially gifted individuals. 'When those who are endowed with this faculty,' he affirmed, 'operate by employing the force of the imagination and the will, this force affects their blood and their spirits, which produce the intended effects by means of an evaporation thrown outwards.' Following Pomponatius, John Baptist von Helmont, to whom medical science owes a great deal, also proclaimed the curative virtue of magnetism, which he described as an invisible fluid called forth and directed by the influence of the human will. Other writers, notably Sir Kenelm Digby, laid stress on the power of the imagination as an agent in the cause as well as the cure of disease, compiling in a curious little treatise published in 1658, as interesting a collection of illustrative cases as is contained in the literature of modern psycho-therapy."