Hermann of Reichenau

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Hermann of Reichenau — known in Latin as Hermannus Contractus, “Hermann the Lame” — was an eleventh-century German Benedictine monk and one of the most accomplished scholars of his age: a chronicler, mathematician, astronomer, music theorist, and student of the calendar. He lived from 1013 to 1054 and spent almost his whole life inside the abbey on the island of Reichenau, in Lake Constance, where he had been given over as a child. He was born on 18 July 1013 into the Swabian comital family of the counts of Altshausen, and on 13 September 1020, at the age of seven, he was entered into the cloister school of the island abbey, then under its reforming abbot Berno. He never left it. The island, with its three churches and its scriptorium, was for him the whole visible world, and out of that small compass he reached the heavens.

The byname and the body

The byname records a fact about his body. Hermann was severely disabled from early childhood — by a condition that left him barely able to move or speak clearly, so that contemporaries marvelled that a mind of such reach worked through a frame so constrained. Later readers have proposed one diagnosis or another — cerebral palsy, a neuromuscular wasting, spina bifida — but these are modern guesses laid over a thousand-year gap, and the sources themselves give only the lived shape of the thing: a man who had to be lifted and carried, who could hold himself upright in a chair only with difficulty, who formed words with labor and wrote with more. The epithet contractus, “the contracted,” the limbs drawn in, attached to his name within a century of his death and has clung to it ever since.

His pupil Berthold, who wrote the account on which most of what is known of him depends, describes a man carried from place to place and able to write only with difficulty, yet producing across his short life a body of learning that ranged over the whole curriculum of the medieval schools. Berthold’s portrait is not a hagiographer’s afterthought composed at a distance; it is the testimony of someone who sat at the lame man’s feet, took down his words, and continued his unfinished chronicle. From that nearness comes the detail that gives the life its peculiar gravity — not the obstacle alone, but the disproportion between the constrained body and the unconstrained range of what passed through it. The monastic ideal held that the soul was not its flesh and that a mind turned wholly toward order could be at home anywhere. Hermann’s life is the hardest case that ideal ever had to carry, and it carried it.

The quadrivium and the proportioned cosmos

That curriculum is where his interest for the history of esoteric thought lies. Hermann worked at the center of the quadrivium — arithmetic, geometry, music, and astronomy — the fourfold mathematical learning that monastic Europe had inherited, by way of Boethius, from the late-antique Platonist tradition. The quadrivium was not four subjects so much as four faces of one subject: number considered in itself (arithmetic), number extended into space (geometry), number unfolded in time as sound (music), and number set turning in the heavens (astronomy). To learn it was to learn that the same ratios underwrote the string, the year, and the sphere. Boethius had given the Latin West its textbooks for two of the four — De institutione arithmetica and De institutione musica — and through him the order of Pythagoras and of Plato’s Timaeus reached an island in a lake in Swabia. Hermann is one of the clearest cases in the eleventh century of a mind that received that inheritance whole and worked at every corner of it.

Behind all of it stood an old conviction, never stated as his treatises’ subject but everywhere assumed: that the cosmos is built on proportion, and that the same numbers govern the scale, the year, and the sky. This is the Neoplatonist and Pythagorean intuition transmitted through Boethius and through Macrobius — the world as a sounded harmony, the soul as a numbered thing, the heavens as audible mathematics made visible. The apparatus Hermann built and refined — the instruments, the reckonings, the tables of ratios — was the same apparatus on which later astrology and number-symbolism would draw. But he himself pursued it as orthodox science in the service of the Church’s calendar, with no horoscope in view: the proportion he sought in the heavens was the proportion of the liturgical year, the dating of the feasts, the agreement of the moon’s month with the sun’s.

The astrolabe and the instruments of the sky

Hermann wrote on the astrolabe, the flattened brass model of the turning heavens by which a single disk could solve at a glance problems of time, the sun’s height, and the rising of the stars. He stands among the earliest Latin authors to carry into the West — from the Islamic world, by way of Muslim Spain — three astronomical instruments at once: the astrolabe, the chilinder (a portable cylindrical sundial), and the quadrant with its sliding cursor. The astrolabe he describes was cut for the latitude of forty-eight degrees, which is the latitude of Reichenau itself; the abstract instrument was fitted to the very sky over his window. Two treatises bear on this work. The De mensura astrolabii, on the construction and graduation of the instrument, has been ascribed to him since the thirteenth century; the De utilitatibus astrolabii, on its uses, is a more tangled case — its first part, dense with Arabic technical terms, was credited in the twelfth century to Gerbert of Aurillac and is not now thought to be Hermann’s, while the later portion describing the chilinder and the quadrant is generally accepted as his.

His astronomy reached past instruments into measurement. In one passage he reports the ancient determination of the earth’s circumference — Eratosthenes’ result as it had come down through Macrobius — and reckons the earth’s diameter from it, using the Archimedean approximation of twenty-two sevenths for the ratio of circle to diameter. The reckoning drew him into one of the rare glimpses of medieval scientific argument we possess: in 1048 he and his former pupil Meinzo of Constance exchanged letters disputing the figures. A monk on an island, his body locked, was corresponding about the size of the planet.

Computus and the ordering of sacred time

Hermann wrote on computus, the demanding art of reckoning the date of Easter and ordering sacred time against the motions of sun and moon. Computus was the applied heart of the quadrivium for a monastery: the whole movable architecture of the liturgical year hung on getting it right, since Easter’s date governed Lent before it and Pentecost after, and Easter itself was fixed by a rule that yoked the solar week to the lunar month — the first Sunday after the first full moon after the spring equinox. To compute it was to make the irregular moon and the steady sun agree inside the Christian year, an act of calendrical engineering that monastic Europe had practiced since the Venerable Bede codified it. Hermann did not merely inherit Bede; he corrected him. His De mense lunari, on the length of the lunar month, takes the great Northumbrian computist to task on a technical point, and in 1042 he set out a reformed lunar reckoning in a short work known as the Abbreviato compoti. The reverence proper to a Benedictine for so authoritative a predecessor did not stop him from following the numbers where they led.

Music as audible number

He composed treatises on musical theory in which the ratios of intervals are read as expressions of number. His Musica is among the most important music treatises of the medieval centuries — a systematic ordering of pitch in the Gregorian chant, built on a theory of intervals and modes that he traces back through Boethius and Ptolemy to the Greeks, and that he sets out by measurement on the monochord, the single stretched string on which a moving bridge makes audible the arithmetic of the octave, the fifth, and the fourth. He names the consonant intervals one by one and assigns each its ratio; he treats the ancient Greek tonal system and the church modes together; and where earlier theorists had described the modes by their melodic shapes, he reorganizes the whole on the principle of position — where a sound sits in the ordered scale — rather than mere form. The same conviction runs under it that runs under his astronomy: that to hear an interval truly is to hear a proportion, and that the consonances of the singing choir are the same harmony that holds the spheres. He is credited as well with composing chant — sequences for the liturgy — so that the theory and the sung practice met in one man.

The chronicle and the antiphons

He is also remembered, by long tradition, as a hymn-writer. The Marian antiphons Salve Regina and Alma Redemptoris Mater have for centuries been ascribed to him, and the attribution still circulates widely; modern scholarship treats it as uncertain rather than secure, since the early evidence is thin and the same hymns are credited elsewhere — the Salve Regina also to Bernard of Clairvaux and to others, on no firmer ground. What is firmer is the Chronicon, his universal chronicle. Running from the birth of Christ to his own day, it was among the first works to gather the scattered events of the first Christian millennium into a single continuous account ordered strictly by the years of the Lord — the anno Domini reckoning that Bede had championed, here made the spine of a whole world history. It is a careful work of dating, and that care was its legacy: his pupil Berthold continued it past his death, and later medieval historians — Manegold of Lautenbach, Otto of Freising — used and extended it. The same exactness that set the date of Easter set the dates of the past.

Sources, editions, and the modern recovery

The recovery of Hermann as a working scientist rather than a pious legend is largely a labor of the nineteenth and twentieth centuries. His astronomical and computistical writings were edited from the manuscripts and sifted for authenticity — the tangle of the astrolabe treatises, the genuine De mense lunari, the disputed pieces — by editors who had to separate his hand from Gerbert’s and from later interpolation. His Chronicon was printed in the great nineteenth-century corpus of German medieval sources and remains the form in which historians read it; an early printed text and the manuscript tradition survive in digitized form, including the full Latin of the chronicle and of the astrolabe treatises in open repositories of patristic and medieval texts at Documenta Catholica Omnia. The standard modern study of his music is John L. Snyder’s critical edition and translation, The Musica of Hermannus Contractus, which establishes the text, traces his debt to Boethius and Ptolemy and to the anonymous Musica enchiriadis, and sets out the position-based theory of the modes that is his own contribution. The concise scholarly life remains the article in the Dictionary of Scientific Biography, which lays out the works, the attributions, and the chronology with the skepticism the legendary accretions require. For the bare facts of date and work, the biographical notice maintained at St Andrews is a reliable summary.

Care is needed not to confuse him with Hermann of Carinthia, the twelfth-century translator who carried Arabic astronomy and astrology — and a share of the first Latin Qur’an — into the Latin language a century later. The two have been run together since the Middle Ages, the more so because both bear the name Hermann and both touch the astrolabe; but they are different men of different centuries and different work. Hermann of Reichenau received the Arabic instruments at the threshold of their arrival in the West; Hermann of Carinthia was one of those who opened the floodgate of translation that followed.

A line of monastic learning

Hermann was beatified in the nineteenth century — his cult confirmed by Pius IX in 1863 — and is venerated in his region as Blessed Hermann. He belongs to the line of monastic scholars through whom the mathematical and astronomical learning of antiquity survived the early Middle Ages — the learning on which later cosmological and divinatory speculation would build, and which would reach a speculative summit two centuries on in figures like Hildegard of Bingen, whose own cosmology sang, and four centuries on in Nicholas of Cusa, who made the proportioned universe a matter of learned ignorance. The thread that ran through all of them — the conviction that number is the form of the world — Hermann held in a single small body on a single small island. He died at forty-one, and Berthold records that he met the end he had long expected with composure.

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