Tractatus de sphaera, Textus de sphaera, or simply De sphaera) is a medieval introduction to the basic elements of astronomy written by Johannes de Sacrobosco...

Tractatus is Latin for "treatise". It may refer to: Tractatus de amore by Andreas Capellanus Tractatus Astrologico Magicus, also known as the Aldaraia...

was named in his memory. About 1230, his best-known work, Tractatus de Sphaera / De Sphaera Mundi (Treatise on the Sphere / On the Sphere of the World)...

a picture of a small paper boat in an edition of Tractatus de sphaera mundi from 1490 by Johannes de Sacrobosco. However it is very likely that paper...

most regarded for his work on Tractatus de Sphaera, which is usually published with other texts on Tractatus de Sphaera from various authors. This opens...

Gilbert de la Porrée's De sex principiis and Summulae Logicales by Petrus Hispanus (later Pope John XXI). The standard work of astronomy was Tractatus de sphaera...

Sphere with the theory of the Sun and the Moon), (1537). From Tractatus de Sphæra by Johannes de Sacrobosco, Theoricae novæ planetarum by Georg Purbach and...

small paper boat in the 1498 French edition of Johannes de Sacrobosco's Tractatus de Sphaera Mundi. There is also evidence of a cut and folded paper box...

wrote an authoritative and influential mediaeval astronomy text, the Tractatus de Sphaera; the Algorismus, which introduced calculations with Hindu-Arabic...

Libellus de sole, originally by Marsilius Ficinus. He then made two different commented reprints of the Tractatus de sphaera by Johannes de Sacrobosco...