Adelard of Bath, an English scholar and linguist who had spent many years travelling, as he said, “for the sake of knowledge,” returned to his native land in the year 1126. He had some particularly unkind things to say about the state of knowledge, especially that form which we would call scientific knowledge, in England and some particularly enthusiastic things to say about the state of scientific learning in other parts of the world that he had seen, places about which his countrymen knew very little. At the outset of his travels, which are quite remarkable in themselves for an...

The Romans, however excellent they may have been in other departments of human activity, had never cared to make the intellectual effort necessary to comprehend fully the science of the Greeks, much less add to it. From the first century B.C. in the works Varro and Cicero, to the sixth century A.D. in the works of Boethius, Cassiodorus and Isidore of Seville, Latin authors compiled handbooks containing, among much else, simplified accounts, sometimes competent but often confused, of portions of Greek science. Besides this, some translations of Greek scientific treatises, especially medical works, were made during the sixth century, many...

The twelfth century was a transitional period in the history of medieval science. The old standard sources (especially Calcidius’ translation of Plato’sTimaeusand his commentary on that work, the various treatises on Boethius, Macrobius’Saturnaliaand Seneca’sNatural Questions) continued to dominate and the newly acquired works were often grossly misunderstood. The striking thing about this century is the attitude of its scientists. These men are daring, original, inventive, skeptical of traditional authorities although sometimes overly impressed by new ones, and above all steadfastly determined to discover purely rational explanations of natural phenomena. These explanations are usually painfully ad...

By the first quarter of the thirteenth century, virtually the entire scientific corpus of Aristotle had been translated into Latin several times, from both Greek and Arabic. Treatises on optics, catoptrics, geometry, astronomy, astrology, zoology, psychology and mechanics by both Greek and Muslim authors were added to these, and after 1231 the excellent commentaries of Averroes on Aristotle’s works became available. Although most of this had been translated during the twelfth century, for several generations it remained known to only a few of the more inquisitive scholars. Around the year 1200 this material began making its way into the curricula...

The tides had been the object of scientific investigation at least since the time of Aristotle, and a smattering of the knowledge of the great Hellenistic investigators had survived in the Latin handbook tradition. In addition, Bede, in hisDe temporum ratione,had made some very important observations on tidal phenomena, as we have mentioned before, including their relationship to the motion of the moon and the principle of the establishment of port. During the twelfth century, the Spanish Moslem Al Bitruji (Alpetragius), as a consequence of his “Aristotelian” astronomy, proposed a new explanation of the tides (summarized and refuted...

One of the most impressive results of the employment of the mathematical experimental method in the Middle Ages was the series of solutions proposed for the very difficult problem of the rainbow. The starting point of these studies was Aristotle’sMeteorology,and the turning point was the work of Robert Grosseteste. They culminated in the work of Theodoric of Freiberg shortly after the beginning of the fourteenth century.

One of the most striking aspects of the study of the rainbow in the thirteenth century is the originality and imagination which accompanied the experimental work. It was generally agreed that even...

It is in the analysis and treatment of local motion that Aristotle’s works are perhaps weakest, and it was in elaborating and criticizing his remarks that medieval scientists did some of their most impressive and fruitful work. The commentators of late Antiquity had attempted some clarification, and both the Muslims and the thirteenth-century Latins had dealt with the problem, but it was not until the early fourteenth century that significant progress was made. This progress resulted for the most part from the rigorous application of mathematics to the study of motion; the experimental side of the question was largely ignored....

Although astronomy was probably the most persistently studied of all the scientific disciplines during the Middle Ages, since it was indispensable in setting the dates of movable feast days, it was nevertheless nearly always considered merely as a practical device for saving the appearances and getting results. Even in the early Middle Ages, scholars were aware of a variety of cosmological schemes devised by the ancients and passed on in the handbooks, so there was never a question of one specific cosmology comnla. nding the adherence of all. Gerbert in the tenth century had adopted the scheme of Pliny, slightly...

The science of the Middle Ages was not completely devoid ofmagical elements, although these are much less prominent than is usually supposed. It was especially in the sciences (or pseudo-sciences) of alchemy and astrology that the magical outlook predominated—that is, cause and effect relationships outside the realm of nature were considered to be operative. Then as now there was a large amount of sheer superstition, and both written magic lore and charlatan “magicians” abounded. What we are interested in in this chapter is the extent to which magical ideas influenced the world view of serious scientists.

There is a...

Despite the fact that many excellent illuminating studies of medieval science, as well as the texts of the works themselves, have been published in easily accessible volumes during the past fifty years, it is not unusual to find even well-educated people abysmally ignorant of the subject. Unfortunately this does not inhibit them from writing authoritatively about it. As recently as 1950, a Cambridge professor, M. Postan, contributed a chapter entitled “Why Was Science Backward in the Middle Ages?” to a book calledA Short History of Science(Garden City, N.Y.: Doubleday and Co. Inc., 1959). While admitting some “purely intellectual...