Antécédents gréco-arabes de la psychophysique by Léon GauthierReview by: George SartonIsis, Vol. 32, No. 1 (Jul., 1940), pp. 136-138Published by: The University of Chicago Press on behalf of The History of Science SocietyStable URL: http://www.jstor.org/stable/226061 .

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I36 Isis, xxxii, I

The publishers have gotten out a handsome volume reminiscent irr binding and format of the earlier Sydenham editions, but with clear and legible type face-altogether a pleasing example of bookmaking.

CHARLES A. KOFOID.

Aristotle.-On the heavens. With an English translation by V. K. C'. GJUTHRIE. XXI-vl, 379 P. (Loeb Classical Library), Cambridge, Mass., Harvard University Press, 1939.

This very convenient edition and translation of the De caelo will be welcome to historians of ancient and mediaeval science who are repeatedly obliged to refer to that text. The new editor has made full use of D. J. ALLAN's emendations and of J. L. STOCKS' interpretation (Oxford trans- lation of ARISTOTLE), as well as of the commentators, from SIMPLICIUS to JAEGER. To indicate the scope of this treatise it will suffice to recall that the Aristotelian heavens meant many things (i) the limiting sphere of the fixed stars, (2) the region between that sphere and the moon, (3) the whole universe. It thus includes discussions of many fundamental topics, such as the aither, the fifth, imperishable, substance (the four elements concem only the sublunar, perishable, world). One of the necessary properties of the aither is that its natural motion is circular, while the natural motion of the four elements is rectilinear, either to or from the center of the Universe and of the Earth. According to ARISTOTLE, the circular motion is unceasing and has no contrary! As is always the case with the Aristotelian writings the modem reader never knows whether he should admire the philosopher's bold abstractions or be scandalized by their wild arbitrariness. At any rate it is clear that such fantastic ideas on motion, on aither, on the finiteness of the universe, etc. were bound to stimulate endless discussions, and it is not surprising that mediaeval literature is chuckfull of them.

To illustrate the intrinsic contradictions of the De caelo, Mr. GunRIE gives a list of the passages which exclude the transcendent mover (that is, a superior and unmoved mover of the spheres and of everything. else), then another list of the passages which imply the transcendent mover, and finally adds a series of relevant passages taken from other Aristotelian writings.

This little book would forn an excellent text for a seminary on ancient and mediaeval philosophy; the historian of inediaeval science will do well to keep it always withini easv reach. GEORGE SARTON.

Leon Gauthier.-Antdcddents grico-arabes de la psychophysique. 104 p. , 5i P. in Arabic. Beyrouth, Imprimerie Catholique, i939.

We have sooken many times of the Arabic studies of LEON GAUTHIER,

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REVIEWS I37

honorary professor at the University of Algiers, the last time apropos of his new edition of IBN TITFAIL (Isis 30, IOO-3). His most recent work is a very pleasant surprise, for it introduces an entirely new idea and increases materially our respect for AL-KINDt (IX-i), much as we admired him already (Introd. I, 559-60).

91U ZAZYI djuvz

Incipit of AL-KINDV'S treatise on pharmacodynanics

This book contains the first edition of a treatise of AL-KnIco's on the knowledge of the properties of composed drugs (fi ma'rifat. quwl'l-adwiya'l-murakkaba) on the basis of the unique Munich Ms., and of the mediaeval Latin translation printed five times between IS3i and i6o2. The Arabic text being defective and sometimes unintelligible, the early Latin translation was very helpful. To that edition Professor GAUrHIER has added a French translation and a most interesting introduction (43 p.) wherein he shows that in his posology AL-KiNDI had anticipated the psychophysical law formulated by ERNST HEINRICH WEBER (I825-I834) and later completed by THEODOR GUSTAV FECHNER (i86o).

The WEBER-FECHNER discovery implied three steps i. taking the smallest perceptible difference as the unit of sensation, 2. correspondence between the geometric progression of excitations and the arithmetic progression of sensations, 3. the sensation is proportional to the logarithm of the excitation. Steps i and 2 were made by WEBER; the third step-a purely mathematical one-was made by FECHNER, who however contributed also to the improvement of the experimental methods. Of course, one could not expect to find step 3 in any writing anterior to the discovery of logarithms, though it is interesting to come across a second physical example (the first being the theory of music, Isis 26, 552) which might have led Arabic mathematicians to that discovery.

The first step is explicit in Greco-Arabic posology. A drug is called

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138 Isis, xxxii, I

" hot " if it introduces in the condition of a man having a " cold " disease, an improvement which the physician is able to perceive. The drug is said to be " hot in the first degree" if the improvement is just perceptible; it is said to be " hot in the second degree " if it is capable of adding a second improvement just perceptible; only four degrees of heat (or cold) are considered. These ideas were certainly derived from those of ARISTOTLE on the nature of motion (Physics VIII); for the discontinuity of motion suggested the discontinuity of sensation. However, the Aristotelian argument precluded the formulation of the psychophysical law. This was left to AL-KINDS, when he tried to find a mathematical correspondence between various drug excitations and the sensations of the patient (or the observations of the physician). Assuming that the numerical laws of nature are as simple as possible, he considered the five kinds of mathematical progressions familiar to him, and retained on a priori grounds the geometrical progression of ratio 2. This was criticized by IBN RUSHD in his Colliget (Mr. GAUTHIER

gives the French translation of the relevant text) in a very curious and abstract manner. Indeed the ideas of AL-KYNDS and IBN RUSHD on that subject might be quoted as an excellent example of a priori reasoning vainly replacing experimental evidence. It would take too long to reproduce M. GAUTHIER's discussion, and it would not be expedient to summarize it; I can only refer the reader to it. In that sense AL-KINDI"s anticipation of WEBER's law is purely accidental; it is no more an anticipation of it than of FECHNER'S law, for it fell as far short of the first on experimental grounds as it did from the second on mathematical ones. Yet the coincidence is very remarkable and will rejoice historians as well as philosophers. GEORGE SARTON.

Raphael Levy and Francisco Cantera.-The beginning of wisdom. An astrological treatzse by ABRAHAM IBN EzRA. LXXVI+235 PP. The Johns Hopkins Press, Baltimore, I939 (price $2.75).

ABRAHAM IBN EzRA (c. I092-II67) (i), admired by the Jews as a poet and philosopher, and above all as the ingenious commentator of the Bible, was known in the Christian world mainly as an astrologer. Between I 146 and I I48 he compiled eight astrological treatises; the most comprehensive and best among them is his Reshith hokhmah, Principium sapientiae, based, as it seems, upon ABO TMA'sHAR's (c. 786-886) great Introduction. In I273-4 HENRY BATE invited the Jew HAGIN to prepare a French translation of the Reshith hokhmnah in his house at Malines (Mechelen), near Antwerp. HAGIN, complying with the request, dictated

(i) According to recent investigations, quoted by LEvy on p. 24, he is supposed to have died in 1i64, in England, most probably in London.

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