Proceedings 35        21 October 1993        the Warburg Institute, Woburn Square, London



Introducing her paper with an allusion to the Society’s proceedings, the speaker observed that a recurring theme was the remergence of Greek philosophy and Roman technology following the 'Dark Ages'" and the infiltration of Hindu-Arabic science. Through this emerged transition to modern scientific method. Thanks to the intellectual activity of the church there was sufficient literacy and numeracy and a (limited) scholarly foundation. The increasing rediscovery of Aristotle posed questions on the primacy of reason. The discovery of the full corpus of Euclid was a crucial turning point. Adelard's contribution here was major.

Born Bath ca. 1080, by 1100 Adelard was attending the cathedral school at Tours. From there to Laon and further travels including Greece and Italy finally, he tells us, he went to Syria to learn from the Arabs.

Returning to England he worked in the Exchequer, wrote his masterpiece Quaestiones naturalis treatises on the abacus, the astrolabe and falconry and translations:-e.g. an Arabic version of Euclid; the Zij of al-Khwarizmi and astrological works.

In 1088 Bath. virtually destroyed by William II in punishment for support to his older brother Robert, was sold by the king to John of Tours, bishop of Wells. He rebuilt the city, transferred the seat of the diocese there and built a palace. two hospitals and a cathedral--Adelard grew up in a period of great cultural activity.

A., the first English scientist, was related to the powerful and wealthy family of 8iso bishop of Wells (John,s predecessor, a Lorrainer and one of Edward the Confessor's numerous reforming appointees) hence his knowledge, no doubt, of falconry. He also played the courtly musical instrument the cithera. Bishop John founded a school at Bath Abbey.


Adelard's de eodem et di verso  ('of the same and the different') forms the obvious start for a study of his ideas, detailing the curriculum he pursued. (It graphically demonstrates the advanced level of learning expected of high administrative officials.) It begins in an allegorical encounter between Adelard and two stately matrons Philosophy (philosophia) and Worldliness (philocosmia) and their attendants as he walked musing along the banks of t.he Loire during his time at Tours. Philosophy is accompanied by seven handmaidens, representinq the Liberal Arts, a favourite medieval scholarly conceit depicted in sculptures on many cathedrals. Worldliness is accompanied by Riches, Honour, Power, Fame and Pleasure. Despite the blandishments of Philocosmia, A. resolves to follow Philosophia, philosophy being the supreme work of human intelligence--beyond which began the work of God--hence its identification with the circle of The Same. The Liberal Arts now parade before him and the nature of each is explained--Adelard preference is clearly for mathematics (he depicts astronomy with an astrolabe which he may have learnt about at Tours).

de eodem discusses the nature of reality, explains a philosophy of non-difference and attempts a reconciliation of Plato and Aristotle on the questions of universals. Adelard concludes that what we see in the physical world is at once genus, species and individual so that Aristotle is right when he insists that universals do not exist except in things of sense. However, in so far as universals cannot be perceived in their full purity by mortals without the exercise of imagination Plato was right to argue that they had a true existence beyond the realm of sense in the divine mind.

Adelard views of course reflected the debate on universals already well launched by Anselm of Canterbury (neo-Platonic realism) and Roscalin, teacher of Peter Abelard (nominalism, i.e. Platonic forms are no more than terms). The problem for theologians was whether the doctrines of the Christian Faith were challenged by Reason. It was worth pointing out that while discussions on logic continued in France, attention in England was directed now towards the new scientific ideas.

After Tours, A. returned briefly to Bath before going to Laon, no doubt to study under the mathematician Ralph of Laon who had written a treatise on the abacus. A number of English students preparing for careers in the exchequer went to Laon. Adelard book on the abacus concentrating on multiplication and division was a practical work yet betrayed his passion for mathematics.

Quaestiones naturales sums up Adelard reflections on natural science and gives full primacy to the use of reason. This emphasis was said to have ‘completely changed the state of natural philosophy’. It was interpreted as advocacy of Aristotelian thought and experimental method. He specifically limited his concerns to natural science, itself a radical new departure. Heretofore the predominant theological interest of scholars had led them to treat the natural world as a kind of shadow of divine power. The context of Adelard use of reason marked the first explicit assertion that recognition of divine omnipotence did not preclude the existence of proximate natural causes knowable by independent scientific enquiry. A. urged investigation of causes:  the mind imbued with wonder [that] contemplates effects without regard to causes never shakes off its perplexity. Look more closely, take circum-stances in their totality, set forth causes and then you will not be surprised at effects. Do not be one of those who prefer ignorance to a close examination. Alistair Crombie had pointed out that the development of this form of rationalisation (making use of a distinction ultimately deriving from Aristotle between experiment [a] knowledge of a fact and rational knowledge of the reasons for or cause of the fact) was part of a general intellectual movement in the 12th c. In the quaestiones A. did not disguise his views in allegorical presentations and claimed that. critics made him ‘the subject of scandal.’ Nevertheless the book circulated widely over the next. 350 years


Adelard"s most important translations from the Arabic were the Elements of Euclid (two other 12th-c.translators--by Hermann of Carinthia and Gerard of Cremona--never matched his in popularity) and the Zij of al-Khwarizmi. Before Adelard, The Elements (Alexandria c.300 BC) were unknown in Latin, whereas the Arabs had two translations from the Greek. Thanks to Adelard. Europeans gained access to one of the great achievements of the human intellect. The importance of his work was great since the study of Euclid revealed the method by which theorems were proved deductively. Marshall Clagett has divided the numerous surviving_versions of_Adelard_ into three groups; ADELARD II-surviving in 56 MSS was the popular text--it was used by Campanus and became the basis of the first printed text and the basis of all editions until 1533.

The appearance of Adelard’s Euclid coincided with the beginnings of Gothic architecture--there was good reason to believe that the one strengthened the other. The book quick1y became the basic geometry text at the cathedral school of Chartres, the most famous mathematical school in the Christian West. Only a few years later a disastrous fire meant a rebuild. it was followed by a second great fire but the west front surviving from the first rebuild of 1145 is conclusive evidence of the basic understanding of geometry which underlay beneath the structural scheme and the decorative sculptures. Euclid himself accompanies the personification of Geometry among 'the figures of .the Seven Liberal Arts who occupy the archivolts surrounding the enthroned figure of the BVM in the right-hand portal. It was to be hoped that A. who was still alive learnt of his contribution to the great cathedral.

NUMBER - AL KHARIZMI’s Zij (astronomical tables)

Adelard translations. of the Zij was perhaps still more important than his Euclid. The Latin world was totally unprepared for such a work, whose scientific and mathematical assumptions far transcended anything in the computus literature. A new technical vocabulary had to be acquired to put it to use. The process of assimilation and understanding was slow and Copernicus was the first to truly master it. The tables included explanations which stressed the importance of the sine and also contained a table of tangent functions where the principles involved would have been familiar to Adelard from his understanding of the shadow function used to convert altitude measurements with a gnomon into angles.

A1-Khwarizmi (fl. 820) had been a key figure in the House of Wisdom of Baghdad founded by Caliph al-Ma’ mun. But the basis of his mathematics was laid a centurv earlier when an Indian skilled in the ‘calculus of the stars’ arrived at the court of al-Mansur (754-75). The visitor had methods for solving equations based on sines (the original Sanskrit word ‘jiva’ meant bowstring) calculated for every half degree and methods for computing eclipses. He also possessed a copy of the Sanskrit astronomical text, the Sidhanta. On the orders of al Mansur this was translated by al-Fazari as the ‘Great Sindhind’~. To help in the preparation of his tables, al-Khwarizmi made a digest of this, the Zij. The original no longer exists making A.~s translation all the more important.

In his introduction Adelard explained the concept of Arim, the zero meridian of Hindu astronomy which al-Khwarizmi employs. Its site in modern terms is that of Ujjain in India, 76 E. of Greenwich and 24 N. Latitude). Not only was it necessary to correlate information about celestial phenomena with one’s own longitude in relation to Arim, but the various calendars used by different nations had to be adjusted. As a result of Adelard’s explanation it has been possible to date his translation as having been done in A.D.1126. He gave thlS as the equivalent of the Arabic year 520 and used it as an example of how the Arabic year of lunar months could be related to the Roman solar year. It is worth noting that though the use of a symbol for zero is an accepted procedure in relation to tables, the cifra r is merely a terminus not a zero in our sense of the term. Adelhard explains the symbol with the words id est nullus.

Another translation  of Al-Khwarizmi's tables based on the same original source but a correlation in terms of 1115-1116 was produced by Petrus Alfonsi, the converted Jewish physician at Henry I's court. A. does not refer to him and we do not know if they collaborated It was apparent, however, that both were predominantly interested in the use of the tables for astrology.

The speaker observed that it was distressing to discover that A. did not apparently understand the procedures he described. For example, in the astrolabe treatise, his last work he explained of the importance of the Arim but then completely miscalculated the longitude of Bath. In conclusion she described how Adelard used the astrolabe when tutoring the young Henry Plantagenet (son of Henry’s daughter Matilda and later king as Henry II an occasional visitor to Bristol held by Robert of Gloucester or his mother against King Stephen. His treatise, dated by Professor North to 1149 when Henry as 16 was dedicated to the young prince. It had some unusual features, for example it began with a cosmography, sensible in a work for a young pupil. A. says that an astrolabe’s alidade (sighting device) could be fitted either with two pinules or a tube to look through.

A small group of 12th-c. horoscopes in the royal collection analysed by Professor North, and based on the al-Khwarizmi tables, may have been the work of Adelard. One of them referred to a meeting between a master and a former pupil. Adelard must have been delighted to end his career by introducing a future k1ng to the wonders of the universe. The astrolabe treatise was his last work.