First he cites from “Aristotle in the Book of Stones,” a spurious treatise of which we shall have more to say in the chapter on Aristotle in the middle ages, a number of examples of the marvelous powers of gems worn suspended from the neck or set in a ring upon the finger. One augments the flow of saliva, another checks the flow of blood. The stone hyacinth enables its bearer to pass safely through a pestilent region, and makes him honored in men’s thoughts and procures the granting of his petitions by rulers. The emerald wards off epilepsy, “wherefore we often prescribe to nobles that their children should wear this stone hung about the neck lest they incur this infirmity.”
From Galen and Dioscorides.
Costa also cites some recommendations of ligatures and suspensions from Galen, such as curing stomach-ache by suspending coral about the neck or abdomen, or the dung of wolves who have eaten bones, which should preferably be bound on with a thread made from the wool of a sheep eaten by that wolf. To Dioscorides are attributed such amulets as the teeth of a mad dog who has bit a man, which will safeguard their wearer from ever being so bitten—and it would be somewhat of a coincidence, if he were—and the seed of wild saffron which, held in the hand or worn about the neck, is good for the stings of scorpions. The Indians are cited for what is a recipe rather than an amulet: stercum elephantinum cum melle mixtum et in vulva mulieris positum numquam permittit concipere. And some say that a woman who spits thrice in a frog’s mouth will not conceive for a year. A number of other examples are given without mention of any particular authority. Some of them, indeed, are very familiar and could be found in many authors, and we shall meet them in other contexts.
Occult virtue.
Costa concludes by saying that he himself has not tested these statements extracted from the works of the ancients, but that neither will he deny them, since there exist in nature many strange phenomena and inexplicable forces. We would not believe that the magnet attracts iron, if we had not seen it. Similarly lead breaks adamant which iron cannot break. There is a stone which no furnace can consume and a fish which paralyzes the hand of the person catching it. These strange properties act in some subtle and mighty fashion which is not perceptible to our senses and which we cannot account for by reasoning.[2634] But it is noteworthy that as in discussing incantations Costa said nothing of demons, so he fails to ascribe occult virtue to the influence of the stars.
On the Difference between Soul and Spirit.
Another treatise by Costa ben Luca, On the Difference between Soul and Spirit,[2635] has little to do with occult science, but gives too good a glimpse of medieval notions in the field of physiological psychology to pass it by. It was translated into Latin by John of Spain for Archbishop Raymond of Toledo in the twelfth century,[2636] and is found in many manuscripts, often together with the works of Aristotle.[2637] Probably by a confusion of the names Costa ben Luca and Constantinus[2638] it was printed among the latter’s works,[2639] and indeed we find very similar views in his Pantegni[2640] and in his treatise On Melancholy. The work has also been ascribed to Augustine,[2641] Isaac,[2642] Avicenna,[2643] Alexander Neckam, Thomas of Cantimpré, and Albertus Magnus.[2644] A different work with a similar title and somewhat similar contents is the De spiritu et anima, which is printed with the works of Augustine[2645] but which cites such later authors as Boethius, Isidore, Bede, Alcuin, St. Bernard, and Hugh of St. Victor, to whom also it has been attributed.[2646] Thomas Aquinas called it the work of an anonymous Cistercian.[2647] But to return to our treatise.
The nature of spiritus.
Costa ben Luca has, as we have hinted, some diverting passages in the fields of physiological psychology. He believes in the existence of spiritus, which is not spirit in one of our senses of that word, but “a subtle body,” unlike the soul which is incorporeal. This subtle spiritus perishes when separated from the body and it operates most of the vital processes of the body such as breathing and the pulse, sensation and movement. The two former processes are operated by spiritus “arising from the heart and borne in the pulsating veins to vivify the body.” The two latter processes are caused by spiritus which arises from the brain and operates through the nerves. Thus spiritus is the cause of life in the body and it leaves this mortal frame with our dying gasp. The clearer and more subtle this spiritus is, the more readily it lends itself to mental processes, while the more perfect the human body, the more perfect the spiritus and the human mind. Hence the intellectual powers of children and women are inferior, and the same is true of races subjected to excessive heat or cold like the Ethiopians or Slavs. Here we have the same views repeated as in the Epistle concerning Incantation. Some physicians and philosophers think that there are two vessels in the heart and that there is more spiritus than blood in the left hand vessel and more blood than spiritus in the right hand vessel. The spiritus in the brain becomes more subtle and apt to receive the virtues of the soul by its passage from one cavity of the brain to another. The less subtle spiritus the brain uses for the five senses; Costa speaks of “hollow nerves” from the brain to the eye through which the spiritus passes for the purpose of vision. The most subtle spiritus is employed in the higher mental processes such as imagination, memory, and reason.
Thought explained physiologically.