Arbor and Incest

Medieval canon law built up elaborate rules prohibiting marriage within kin groups. The principles of this were taught with a diagram known as the arbor juris, the first forms of which are classical in origin. The 64 uploads to Digita Vaticana on November 11, 2015 include Urb.lat.160, a mid-14th-century manuscript of decretals or codified canon law preceded by a particularly colourful arbor juris.

This class of diagrams was very comprehensively studied 1973-1982 by Hermann Schadt, who ordered the main group known as the arbores consanguinatis into seven main types. Urb.lat.160 contains the seventh of these types and was designed in the Decretum Gratiani (pars II, causa 35, qu. 5), a collection of canon law compiled in the 12th century by a jurist who is known as Gratian. At first it condemned a very wide range of potential marriages (some of the 14th degree by the classical Roman method of counting), but its scope was reduced in 1215.

I have compiled a "missing manual" to Schadt's  magisterial but not very reader-friendly book, and from it comes the following schematic. It shows the post-1215 form of Typ 7. Each roundel describes a relationship which was an impediment to marriage. The pink roundels in this matrix mark the kin relationships counted as third degree by the classical method:

The newly digitized manuscript contains miniatures which are probably genuine work of Nicolò da Bologna (see Italian biography). As Schadt explains, the Typ 7 diagrams developed an interesting iconography: an elderly man, perhaps representing the jurist, held the matrix in front of him as if it were a wooden placard. Tree branches grew to his left and his right, in his grasp. The Nicolò versions of these generally have six busts on the margin, male on the left, female on the right, apparently representing three generations of persons reacting with disappointment to the news that their love object is out of bounds.

The manuscript's arbor consanguinatis is followed by an arbor affinitatis, a large invariant type, which lists the in-laws that a person was also forbidden to wed. Schadt discusses this arbor on p. 276 of his book comparing it to other manuscripts. He notes the miniature's finely drawn depiction of Adam and Eve eating the forbidden fruit and then being expelled from Paradise by an angel:

Here is the full list of the new uploads:

1. Arch.Cap.S.Pietro.B.79, liturgical music. Aaron Macks (comment below) points out it is one of the few manuscripts of "Old Roman" chant. More details at Waterloo.
2. Arch.Cap.S.Pietro.D.194, Postillae on Old Testament, Nicholas of Lyra
3. Arch.Cap.S.Pietro.E.26, mould ravaged Rufinus, Historia Monachorum
4. Arch.Cap.S.Pietro.E.28, Plutarch Lives, in Latin translation by Jacobus Angelus
5. Arch.Cap.S.Pietro.E.30, Justinus, Universal History
6. Barb.lat.3912, poetry of Luigi Pulci
7. Borg.ar.95, Four Gospels in Arabic, 8th century?
8. Borg.cin.507, a beautiful map in Italian of the Qinqhai region of China
9. Borg.copt.109.cass.XII.fasc.41, three folios in Coptic from Matthew 16-18 with marginal illuminations
10. Borg.pers.19, Gospels in Persian, 14th century
11. Cappon.103,
12. Cappon.140,
13. Cappon.239,
14. Cappon.281.pt.2,
15. Cappon.291.pt.2,
16. Urb.lat.14, Postillae of Nicholas of Lyra on Genesis, etc. with a technical discussion of angels guarding the ark of the covenant. Compare this to William Norton's 1403 bid to classify ark styles, based on Nicholas's work. Here is one of the Urb.lat.14 images:
    
17. Urb.lat.18, Peter Lombard
18. Urb.lat.39, Ambrose of Milan, William of Canterbury, Prosper of Aquitaine
19. Urb.lat.57, Jerome on Ezekiel
20. Urb.lat.102, Venerable Bede,  Leo the Great,
21. Urb.lat.103, Richard of St Victor, Hugh of St Victor including his heavenly hierarchy
22. Urb.lat.136, Thomas Aquinas
23. Urb.lat.140, Thomas Aquinas
24. Urb.lat.157, Innocent IV, decretals
25. Urb.lat.158, Azo of Bologna, decretals
26. Urb.lat.160, Johannes Andreae, Boniface VIII, decretals dealing with marriage and other legal issues (see above)
27. Urb.lat.198,
28. Urb.lat.202,
29. Urb.lat.205, Aristotle, 16th century
30. Urb.lat.206, Thomas Aquinas on Aristotle
31. Urb.lat.213, Thomas Aquinas on Aristotle
32. Urb.lat.214, Thomas Aquinas and Robert Kilwardby (?)
33. Urb.lat.215, Thomas Aquinas and Pseudo-Augustine
34. Urb.lat.225, Pontanus Jovianus
35. Urb.lat.229, Leon Battista Alberti
36. Urb.lat.230, Egidius de Columna, Thomas Aquinas
37. Urb.lat.231, Fabius Albergatus on the republic
38. Urb.lat.246, health (urine), astrology, some by Abu-Bakr Razi
39. Urb.lat.250, De plantis, De causis plantarum: a mid-15th-century manuscript of the works of Aristotle's pupil Theophrastus, originally owned by Pope Nicholas V (1397-1455) to whom the manuscript is dedicated on fol. 2r.: see the SLU catalog and the Rome Reborn catalog note, where Grafton points out these were both an important source of information and a stimulus to further contributions to knowledge, but notes that "despite its handsome title page, this volume contains no illustrations intended to help understandings of its scientific content."
40. Urb.lat.256,
41. Urb.lat.258,
42. Urb.lat.259,
43. Urb.lat.263,
44. Urb.lat.268,
45. Urb.lat.269,
46. Urb.lat.271,
47. Urb.lat.279,
48. Urb.lat.292, Fibonacci, geometry, with lots of marginal figures
49. Urb.lat.297, various; grammar, Plutarch
50. Urb.lat.595,
51. Urb.lat.1418,
52. Vat.ar.71, translations of Greek Christian works into Arabic, dated 885 CE
53. Vat.ebr.125,
54. Vat.ebr.263,
55. Vat.lat.97, Peter Lombard, Commentary on Psalms
56. Vat.lat.128, 12th-century, commentary on Mark
57. Vat.lat.152, 13th-century commentary on Catholic Epistles
58. Vat.lat.167, Nicholas of Lyra on Four Gospels, dated 1482
59. Vat.lat.184, Lilius Tifernas
60. Vat.lat.198, Cyprian of Carthage, 15th century
61. Vat.lat.199, ditto
62. Vat.lat.200, ditto
63. Vat.lat.294, Ambrose of Milan, De officiis ministrorum libri I-III.
64. Vat.lat.297,Ambrose, De excessu fratris sui Satyri

Please use the comments box to contribute more details. Follow me on Twitter (@JBPiggin) for more news on Rome manuscripts. [This is Piggin's Unofficial List 30.]

Schadt, Hermann. Die Darstellungen der Arbores Consanguinitatis und der Arbores Affinitatis: Bildschemata in juristischen Handschriften. Tübingen [Germany]: Wasmuth, 1982.

Piggin, Jean-Baptiste. The Missing Manual: Schadt's Arbores. Academia.edu, 2015.