THE BEGINNINGS OF MEDIEVAL INFORMATION VISUALIZATION - Information Visualisation: Techniques, Usability and Evaluation - page 18

space was most likely made for its insertion, possibly at the author's
direction. This is the case in Macrobius' Commentary , where a space was
left for a figure (c.f. Fig. 1.1). It should hold true for Boëthius and Isidore
as well, since their texts explicitly refer readers to explanatory diagrams.
Fixing invention is another matter. The visualizations of each author
discussed here have conceptual antecedents. Macrobius' zonal map of the
earth in Fig. 1.1 dates back to the Pythagoreans with references to the
cosmography of Eratosthenes (c. 275-194 BCE), Posidonius (c. 151-35
BCE), and Crates of Mallos (c. 168 BCE) [38]. Yet, until Macrobius, there
seems to be no physical record of a diagram of this kind.
Boëthius's arc diagrams, in their simplest form, have been used for
logic. Their application is traceable to Plato's works, such as Timaeus and
The Republic , and may have been used as far back as Pythagoras [39].
However, none have been found in any copies of the original versions of
these manuscripts [40].
Isidiore's rota shown in Figs 1.5-1.8 may be seen to mirror Greco-
Roman designs. The twelve divisions of his calendar (Figs 1.5 and 1.6) are
reminiscent of zodiac wheels. The zodiac is a circle divided into 12 parts,
each denoted by a sign that represents the perceived path of the sun along
the ecliptic as it crosses the celestial sphere during the course of a year.
The partition of the ecliptic into the zodiac originated in Babylonia during
the first half of the first millennium BCE, eventually finding its way into
Greco-Roman culture [41]. Zodiac wheels have been found in mosaics
from the Greco-Roman era, particularly in Jewish synagogues throughout
Palestine. 6 One example is a mosaic calendar floor in the Hammath
Tiberias synagogue (fourth century CE) shown in Fig. 1.9. It exhibits a
tripartite structure composed of: a zodiac cycle (ring), four women
representing the seasons of the year (outer corners), and the sun god
Helios riding on a chariot through the heavens (centre medallion) [45, p.
189].
Variations on this schema abound. For example, a second century
Roman mosaic of Neptune shown in Fig. 1.10 contains a central medallion
bounded by women representing the four seasons. Winter is the most
heavily clothed of the four, surrounded by branches of winter berries.
Moving counter-clockwise from winter in the lower left corner brings
spring with blossoms, summer with ripened wheat, and autumn amid
grapes. In a fourth century mosaic from Dorset, England, shown in Fig.
1.11, the schema is rendered more explicitly with a central roundel
6. Zodiac wheels have been found in Greece (Tallaras Baths, Astypalea, 5 th C. CE)
[42]; Tunisia (c. 3 rd C. CE), now in the Bardo Museum; and Palestine (4 th -6 th C.
CE)[43].