tion and its needs.' This was practically giving to the nature-soul of the ancient Greeks a selective capacity. In the 9th and 10th centuries the Arabs applied the same doctrine to the magnet. Serapion says that a solvent medicine, when it reaches the stomach, then draws with an attractive virtue the humor suitable to itself, but it is not drawn to the humor; just as the magnet moves the iron to itself, but is not moved to the iron. Ali ben Abbas likewise makes a similar comparison,3 which, in later writers, is repeated over and over again, although it is essentially false, and simply due to the iron being more weakly magnetized than the attracting lodestone.

The doctrine of similitudes is thus a mediæval form of the old canon similia similibus, and rests on the same concepts. All compounds, for example, were supposed to derive their qualities from their elements by resemblance, being hot by reason of a hot element, heavy in virtue of a heavy element, and so on. For a long period, medical science rested on these distinctions, disorders being hot and cold, and remedies being similarly classified. One Eastern story teller relates that the Persian physicians were scandalized by the prescription of mercury by a European brother, for the cure of ill-effects following over-indulgence in cucumbers; for, they maintained, cucumbers are cold, and hence their ill-effects can not be overcome by mercury, which is cold also. "He makes no distinction," complain the oriental practitioners, "between hot and cold diseases and hot and cold remedies, as Galenus and Avicenna have ordered, but gives mercury as a cooling medicine."

'Martin: Obs'ns and Theories of the Ancients on Magnetic Attractions and Repulsions. See also Atti dell' Accademia Pont. de Nuovi Lincei, T. xviii., 1864-5.

2 Steinschneider: Intorno ad alcuni passi di Opere del Medio Evo relativi alla calamita. Rome, 1868.

3 Lib. Practicae, lib. ii. c., 53.

4 The Adventures of Hadji Baba. Ed. by J. Morier, N. Y., 1855, p. 98.

ALEXANDER NECKAM.

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Similar notions persisted among the metallurgists until the beginning of the 18th century. Thus the ready combination of metals with mercury to form amalgams was regarded as proof of mutual benignant regard, and the combination of metals in their alloys was similarly explained. Lead is loved by gold and silver, but brass abhors lead. The astrologers claimed that metals exercised a selection in benevolently mixing with various parts of the human body, the gold seeking the heart; silver, the brain; lead, the spleen; mercury, the lungs; tin, the liver, and so on. But to living beings as units, they thought that metals manifested great contrariety, because, as it was gravely pointed out, no animal could subsist on metals, plants do not flourish where metallic veins abound, and in mines the vapors are deadly. Even in preparing pearls as medicine, they must be brayed in marble mortars, because otherwise iron might thus be imported into the body and act malevolently.

Neckam follows these ideas closely. Some things, he says, are drawn naturally, others by accident, and when by accident, either from necessity or chance similitude; from necessity, as when the body, through hunger, attracts so that its famishing members will thrive on insufficient food, such as bran (there were evidently dyspeptics in those days), or even on noxious herbs. Accidental similitude occurs when non-nourishing things are combined with nutriment. Natural attraction takes place, we are told, in many ways, "as by the power of heat, or by a virtue, or by the natural quality of similitude, or by the law of vacuity.” Fire, for example, by the strength of heat draws oil for its nutriment.

The concept of an "attractive" virtue is the mediaval modification of Galen's selective vital force. This attraction by virtue, says Neckam, is caused in two ways, either occultly or manifestly. Occult virtue is closely allied to similitude in its effects, and acts as scammony draws bile

1 Aldrovandus: Musaeum Metallicum, ii.

and hellebore the vapors. But manifest virtue is virtue that is perceptible and-here we suddenly find ourselves within the borders of the particular field which we are exploring-it is seen when the lodestone draws iron and the jet chaff.

This reference to jet is noteworthy. The ancient writers spoke of "gagates," which acted like amber, and left it in doubt what gagates might be. After jet had been certainly determined to possess the amber quality, the word was so interpreted. Neckam, however, is not quoting from any ancient author, but stating his own facts and beliefs; and the frequent later use of the English word “jet” by English writers instead of "amber," in referring to the phenomenon figuratively, renders it altogether probable that the learned Abbot was speaking not of the doubtful substance from Lydia, which he had never seen, but the lustrous black stone which had been mined in his own country ever since the Roman invasion.1

"If you ask its value as an ornament," he says, "jet is black and brilliant: if its nature, water burns it and it is extinguished by oil: if its power, being heated by rubbing, it holds things applied to it, like amber: if its use, it is an excellent remedy for dropsy." It was commonly found in Derbyshire and Berwick, and the Romans preferred it to that which was found in Germany. "The old writers," says Harrison," "remember few other stones of estimation to be found in this Island, than that which we call 'geat,' and they, in Latin, 'gegates.'"

The explanation of "the quality of natural similitude not without attractive virtue" is ushered in by an illustration borrowed evidently from the Arabs. A warm stomach draws warm nourishment, and a cold stomach, cold nourishment: and we are to note that, according as by friendly

1 'The value of jet and of Kimmeridge coal for ornamental purposes was then well understood, and jet ornaments have been found in graves of the period. Traill: Social England, i. 92.

2 Harrison: A Description of England. London, 1577.

SYMPATHIES AND SIMILITUDES.

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similitude, attraction occurs, so, by hostile dissimilitude expulsion takes place. So that, for example, if vinegar and water be poured around a tree, the water will be absorbed and the vinegar rejected.

Now comes the first faint suggestion of the polarity of the lodestone. "So," he says, continuing his illustration, "the lodestone attracts by one part by similitude and from another part expels by dissimilitude." This is not the mere statement that a lodestone will repel as well as attract: nor is it, on the other hand, quite the affirmance of "opposite effects at opposite ends," but it is a clear recognition that one and the same stone will repel at one part and attract at another part. Where these parts were situated with reference to the figure of the magnet-whether at its ends or otherwise-Neckam did not know; but that this dual property exists in it, he makes plain. Compare Neckam's statement with that of Aldrovandus written four centuries later; "the lodestone attracts iron by natural sympathy at one end and repels it by antipathy at the other."

Continuing, he explains that the appetite virtue draws by friendly similitude, and the expulsive virtue rejects by hostile dissimilitude; but the attracting thing-again he goes back to the Arabs-must act more violently than the attracted thing, for if equal they would counterbalance. Whence it is that the lodestone draws iron and not another lodestone, although it may have thereto greater similitude, because the lodestone opposes to the lodestone an equal and mutual contradiction. The iron yields itself because of weaker virtue.

The entanglement of his mind in the snares of sympathies and similitudes is obvious. On the theory of similitude, a lodestone should attract another lodestone; but that, he holds, is not the fact. Similia similibus cannot be at fault; that would be to dispute the hypothesis, which is indisputable. Wherefore, query, how can an incontrovertible fact be reconciled with an indisputable theory when they diametrically disagree?

The dialectical subtlety of the problem cannot have been otherwise than fascinating to the intellect skilled in the casuistries of the Petit Pont, and it grappled with the difficulties just as it had perhaps many a time done with "Whether angels in moving from place to place

Pass through the intermediate space"

-and emerged triumphantly.

The similitude is undeniable; so, likewise, the sympathy. One lodestone resembles and sympathizes with the other, even as the other does with it. Therefore, why should attrahens act upon attractum any more than attractum upon attrahens? If Sortes and Scholasticus at opposite ends of a rope pull against one another with equal strength, is Sortes drawn to Scholasticus or Scholasticus. to Sortes? Certainly not; they remain quiescent in statu quo; so do the lodestones. Q. E. D.

Now, this is not setting up Sortes-that favorite straw man of the schools-to be proved a stone, or a rose, or a lily, or what not; nor does it demonstrate that any remark of Sortes is both true and false at one and the same time, nor that he knows something, yet nothing—all favorite quibbles of the mediæval disputants—and, therefore, what Neckam calls "vacuities": this is what a 12th century mind, trying to break away from that sort of reasoning, manages to accomplish in the effort. The reasoning is wrong, of course; but it is physical reasoning, and that, even if wrong, is something better than “vacuities.”

Now follows in this old treatise of an English monk probably the first of all known descriptions of the mariner's compass. Here it is:

"The sailors, moreover, as they sail over the sea, when in cloudy weather they can no longer profit by the light of the sun, or when the world is wrapped in the darkness of the shades of night, and they are ignorant to what part of the horizon the prow is directed, place the needle over the magnet, which is whirled round in a circle, until,