Severus Sebokht

Severus Sebokht, also Sebokt, Sebukht, Seboht, (c. 575 in Nisibis, Syria, † 666 or 667 in Kennesrin, Syria ) was a Syrian Nestorian bishop and astronomer. He was a great scholar in the Late Antique Syria.

About his life little is known. He taught in the school of Nisibis (then Persian), gave his position but after a dispute within the Nestorians 612. Later he became a bishop in the Syrian Monophysite Church and became a monk in the monastery of Kennesrin on the west bank of the Euphrates, at that time one of the centers of Greek scholarship in Syria.

He wrote a book on Aristotelian syllogisms 638 and translated the Persian commentary by Paul Persia on Aristotle De interpretatione into Syriac. He is mainly known for his astronomical works, especially his treatise on the astrolabe (before 661 to 660), in which he refers to a lost work by Theon of Alexandria. The book ( are not obtained from the two chapters ) discussed in detail the construction and use of the astrolabe. He also wrote a book on constellations ( and elementary astronomy, for example, the ecliptic, climate zones and day length ), created 661 after his book on the astrolabe. This book is not completely preserved. It contains extracts from the Phenomena of Aratus and shows familiarity with Ptolemy's hand panels. To 665 he wrote additional chapters in response to questions of the visiting clergy, Basil of Cyprus. They concern among other things, the date of Christ's birth, conjunction of the planets and the calculation of the Easter date.

From Severus Sebokht comes the earliest mention of the Indian decimal system in the "West ". Sebokht praises the decimal system of the Indians. In the 7th century, the Arabs also got to know the system. Arab books that used it, but only appeared in the 9th century ( Algoritmi numero di indorum of Al- Khwarizmi to 825, only in a Latin translation known).