Apparently the duo was considered part of the family.
We need mention only the chief of them - the Collectio Anselmo dedicata, by an unknown author of the end of the 9th century; the Libri duo de synodalibus causis et disciplinis ecclesiasticis, 3 compiled about 906 by Regino, abbot of Pram, and dedicated to Hatto of Mainz, relatively a very original treatise; the enormous compilation surchard.
9 De Vita propria sermonum inter liberos libri duo (Haarlem, 1817).
Have the usual meaning (Duo = u l - uo, L 2 uo = Du 1 - Auo, .
In his principal work, De docta ignorantia (1440), supplemented by De conjecturis libri duo published in the same year, he maintains that all human knowledge is mere conjecture, and that man's wisdom is to recognize his ignorance.