Alkindi’s treatise De somno et visione, as we have it in the Latin translation by Gerard of Cremona,[2601] accepts clairvoyance and divination by dreams as true and asks why we see some things before they happen, why we see other things which require interpretation before they reveal the future, and why at other times we foresee the contrary of what is to be.[2602] His answer is that the mind or soul has innate natural knowledge of these things, and that “it is itself the seat of all species sensible and rational.” Vision is when the soul dismisses the senses and employs thought, and the formative or imaginative virtue of the mind is more active in sleep, the sensitive faculties when one is awake.
Weather prediction.
While by some persons, at least, opinions of Alkindi in his Theory of the Magic Art were regarded as erroneous, Albertus Magnus in his Speculum astronomiae listed among works on judicial astrology with which he thought that the church could find no fault “a book of Alchindi” which opened with the words Rogatus fui.[2603] This is a work on weather prediction which still exists in a number of manuscripts[2604] and was printed in 1507 at Venice, and in 1540 at Paris, together with a treatise on the same theme by Albumasar, of whom we shall say more presently.[2605]
Alkindi as an astrologer.
A majority, indeed, of the works by Alkindi extant in Latin translation are astrological.[2606] Several were translated by Gerard of Cremona, and one or two by John of Spain and Robert of Chester.[2607] Geomancies are attributed to Alkindi in manuscripts at Munich.[2608] Loth notes concerning Alkindi’s astrology what we have already found to be the case in his theories of radiation and magic art and of divination by dreams; namely, that while he believes in astrology unconditionally, he tries to pursue it as a science in a scientific way, observing mathematical method and physical laws—as they seemed to him—while he attacked the vulgar superstitions which were popularly regarded as astrology.
Alkindi on conjunctions.
The astrological treatise by Alkindi, of which Loth edited the Arabic text, is a letter on the duration of the empire of the Arabs. This bit of political prediction was, as far as Loth knew, the first instance of the theory of conjunctions in Arabian astrology. The theory was that lesser conjunctions of the planets, which occur every twenty years, middling conjunctions which come every two hundred and forty years, and great conjunctions which occur only every nine hundred and sixty years, exert a great influence not only upon the world of nature but upon political and religious events, and, especially the great conjunctions, open new periods in history. Thus, as Loth says, the conjunction is for the macrocosmos what the horoscope is for man the microcosmos; the one forecasts the fate of the individual; the other, that of society. Loth knew of no Latin translation of Alkindi’s letter, and medieval writers in Latin cite Albumasar usually as their authority on the subject of conjunctions. But Loth held that Albumasar, who was a pupil of Alkindi, merely developed and popularized the astrological theories of his master, and Loth showed that Albumasar embodied our letter on the duration of the Arabian empire in large part in his work On Great Conjunctions without mentioning Alkindi as his authority.
Alkindi and alchemy.
Although a believer in astrology to the point of magic, and not unacquainted with metals as his work On the Properties of Swords shows, Alkindi regarded the art of alchemy as a deception and the pretended transmutation of other metals into gold as false.[2609] He affirmed this especially in his treatise entitled, The Deceits of the Alchemists, but also in his other writings.[2610]
Astrological works of Albumasar.