In this book he apparently speaks of nothing but supernatural occurrences. Any one reading it as it stands must believe that the author is talking of conjurations of spirits, of spirits flying through the air, and so on. If, however, one drops certain words and letters under the table, there remain--as Wolfgang Ernst Heidel proved in the year 1676--letters which, combined into words, describe purely natural occurrences. (In one case, for instance, in a formula of conjuration, one must drop the first and last words entirely, and then cancel from the remainder the second, fourth, sixth, and so on. In the words left over, one must again cancel the first, third, fifth letters and so on. One next combines what is then left into words; and the conjuration formula resolves itself into a purely natural communication.) How difficult it was for Agrippa to work himself free from the prejudices of his time and to rise to a pure perception is proved by the fact that he did not allow his “Occult Philosophy” (_Philosophia Occulta_), already written in 1510, to appear before the year 1531, because he considered it unripe. Further evidence of this fact is given by his work “On the Vanity of the Sciences” (_De Vanitate Scientiarum_) in which he speaks with bitterness of the scientific and other activities of his time. He there states quite clearly that he has only with difficulty wrenched himself free from the phantasy which beholds in external actions immediate spiritual processes, in external facts prophetic indications of the future, and so forth. Agrippa advances to the higher knowledge in three stages. He treats as the first stage the world as it is given for the senses, with its substances, its physical, chemical and other forces. He calls Nature, in so far as it is looked at on this level, “elementary Nature.” On the second stage, one contemplates the world as a whole in its natural interconnection, as it orders things according to measure, number, weight, harmony, and so forth. The first stage proceeds from one thing to the next nearest. It seeks for the causes of an occurrence in its immediate surroundings. The second stage regards a single occurrence in connection with the entire universe. It carries through the idea that everything is subject to the influence of all other things in the entire world-whole. In its eyes this world-whole appears as a vast harmony, in which each individual item is a member. Agrippa terms the world, regarded from this point of view, the “astral” or “heavenly” world. The third stage of knowing is that wherein the spirit, by plunging deep into itself, perceives immediately the spiritual, the Root-Being of the world. Agrippa here speaks of the world, of soul and spirit.