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Decem tractatus astronomiae by Guido Bonatti, 14th century

Identifier: MS 125


This manuscript was created in the 14th century, probably in England or France. It features work by Guido Bonatti, one of the most celebrated astrologers of the 13th century. He lived in Italy, served as an advisor to Frederick II, and was a mathematician, astronomer, and astrologer. The manuscript contains Decem tractatus astronomiae (Ten Treatises on Astronomy), which are related to his Liber astronomicus and Liber introductorius ad judicia stellarum (Introduction to the Judgements of the Stars).

The contents are as follows:

The Fly-leaves contain unidentified notes and a list of contents that seems to refer to another manuscript.

There is a Prayer on f. 1r, which reads Oret voce pia pro Petro Virgo Maria. This could refer to the scribe.

The Liber introductorius ad judicia stellarum also starts on f. 1r, with the following incipit: In nomine domini Amen. Incipit liber introductorius ad judicia stellarum, et est non solum introductorius ad judicia, sed est judiciorum astronomie editus a Guydone bonacto de forlivio. Et collegit in eo ex dictis philosophorum ea quae visa sunt sibi fore utilia ad introducendum volentes intendere judiciis astrorum et ea quae videbuntur competere volentibus judicare secundum signiiicationes stellarum. Et ad alia quibusdam ipsis judiciis pertinencia. The text of this introductory section also starts on f. 1r, with the words In nomine Dominus Noster Jesus Christus misericordis et pii veri dei et veri hominis. It ends on f. 1v with revolutionis sive pluvias et ymbres.

Tract One starts on f. 1v. It is titled Incipit Tractatus I. Ad ostendendum utilitatem quam possumus sequi de astronomia et de judiciis and starts with the words Anima est nobilius quae reperitur in nomine. It ends on f. 9r with the words esse scientiam manifeste probatur. Finit tractatus primus de confirmatione hujus scientie.

The First Part of Tract Two starts on f. 9r. It is titled Incipit tractatus secundus de divisione orbis signorum and starts with the words Dicam igitur vel vestigia venerabilium predecessorum. It ends on f. 13r with the words in aliis temporibus hyemalibus. Finit prima pars secundi tractatus.

The Second Part of Tract Two starts on f. 13r. It is titled Incipit secunda pars secundi tractatus de esse circuli essentiali and starts with the words In hiis que predicta sunt in isto tractatu. It ends on f. 24v with the words et ita de ceteris intellige. Finit pars 2.2 tractatus.

The Third Part of Tract Two starts on f. 24v. It is titled Incipit tercia pars 3 [sic] tractatus and De divisione circuli per domos. This part starts on f. 24v with the words Accidit circulo signorum divisio and ends on f. 40v with et fortuna videt ei favere. Finit tractatus 2 de divisione circuli signorum.

The next part is titled Incipit tractatus 5 de naturis 7 planetarum et quid sit illis proprium and starts on f. 40v with the words Postquam perventum est ad perfectionem ejus. It ends on f. 53r with the words aliqua dissimilitudo et similia. Finit 3 pars secundi tractatus.

Tract Three starts on f. 53r. It is titled Incipit tertius tractatus de hiis qui accidunt planetis in semetipsos et quid accidit uni eorum and starts with the words In isto tercio tractatu dicendum est. It ends on f. 63r with the words et in boni collatione atque fortunii et tempore. Finit tractatus tercius.

Tract Four starts on f. 63r. It is titled Incipit tractatus 4 de consideracione quarundam conjunctionum et quorundam aliorum que oportet astrologum scire et considerare and starts with the words Iste tractatus est de fortioribus qui sint. It ends on f. 67r with the words ut rectior servetur ordo.

The Tractatus in consideracionibus que cadunt super judiciis secundum motus et significata stellarum starts on f. 67r. It is titled as above and starts with the words Ex hiis autem que ad judicia spectant. It ends on f. 92v with the words i tibi placuerit perscrutari. Expliciunt consideraciones.

The Introductorium sub brevi loquio ad judicia stellarum starts on f. 92v. It is titled as above and starts with the words Cum ad astronomie judicia pervenire intenderis. It ends on f. 95v with the words de ipsis loquentibus invenitur tantum.

The Tractatus super praecipuis judiciis astrorum starts on f. 95v. It is titled as above and starts with the words In isto primo capitulo agendum est. It ends on f. 167v with the words significat augmentum malitie. Explicit tractatus interrogationum seu questionum.


A good Gothic hand, with blue and red filigree initials.


  • Creation: 14th century


Language of Materials


Conditions Governing Access

The collection is open to all. The manuscripts can be consulted in the Centre for Research Collections, Edinburgh University Main Library.


1 bound MS volume

Custodial History

Probably an English or French manuscript. The Petro who is prayed for on f. 1r, at the beginning, may possibly be a scribe.

The only marks of ownership are in an early 16th century hand on ff. 165v and 166v. The inscription on f. 165v reads Due Wecarie de Kyr citetis ligitime Donald McIorous cum sua quod comperiat coram nobis sen substitutis nostris pluribus ant uno. The inscription on f. 166v reads, Be it kenit til al men be yir present letteris yatt Patrick of [S]trewlyn has salde al his Rychttis of his fadirs buks til his derest brod[ir?] Jorg of Strewlyne. The significance of the inscriptions is not very clear, but the volume would appear to have been in the possession of the Stirlings of Keir. It was in any case in Scotland in the 16th century, and later came into the library of the Erskines of Alva (See the Press Catalogue of the Library of Lord Alva, Edinburgh University La.III.755) and thence into this Library.

The Tabula on the fly-leaf refers to another volume altogether and the first few leaves are damaged at the corners.

Previous reference

D. b. II. 8.

Previous title

Title given to the manuscript in Catherine Borland’s catalogue: Guidonis Bonacti de Forlivio Introductoria ad Judicia Stellarum.

Physical Facet

Material: Vellum

Binding: Modern, lettered 'Book of Judicial Astrology.'

Collation: a12-m12, n10, o12, p1=167


28.58 cm x 19.69 cm


Secundo folio: [an]geli neque filius

Foliation and number of lines to a page: ff. 167, double columns, 43 lines to a page.

Repository Details

Part of the University of Edinburgh Library Heritage Collections Repository

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