2. The doctrines concerning the devil, which have held sway for so long a period over the minds of human beings, so enormously exaggerated the power he was supposed to possess, that they caused humankind to lose sight of God; for which reason, human beings gave the devil the credit for anything that seemed to surpass the possibilities of human power. People saw the hand of Satan in everything; the most excellent innovations, the most useful discoveries, and especially those that tended to draw people out of their ignorance and to enlarge the circle of their ideas, have often been regarded as diabolical. Spirit phenomena, being at once of more frequent occurrence at the present day, and also – with the aid of sharper reason and increased scientific knowledge – more intelligently observed than was the case in former times, have confirmed, it is true, the belief in the intervention of occult intelligences in the affairs of human life, but they have shown us that these intelligences always act within the limits of the laws of nature and reveal, by their action, the existence of a force and of laws hitherto unknown to us. The question is therefore narrowed to the ascertainment of the order to which these intelligences belong.
While men and women possessed only vague or empirical notions regarding the spirit-world, error, as to the nature of that world, was inevitable; but now that careful observation and experimental investigation have thrown new light on the nature of spirits, on their origin and destiny, on the part played by them in the universe, and on their mode of action, the question of their nature is answered by facts, and we know with certainty, that spirits are simply the souls of those who have lived upon the Earth. We also know that the various categories of good and evil spirits are not composed of beings of different species, but of spirits at various degrees of advancement. According to the rank which they occupy in virtue of their intellectual and moral development, those who manifest themselves do so under widely different aspects; but this does not prevent their having all issued from the great human family, as is the case with the savages, the barbarians, and the most highly civilized nations of the Earth.