What is "calcidius"

Calcidius (or Chalcidius) was a 4th-century philosopher (and possibly a Christian) who translated the first part (to 53c) of Plato's Timaeus from Greek into Latin around the year 321 and provided with it an extensive commentary. This was likely done for Bishop Hosius of Córdoba. Very little is otherwise known of him.

His translation of the Timaeus was the only extensive text of Plato known to scholars in the Latin West for approximately 800 years. His commentary also contained useful accounts of Greek astronomical knowledge. In the 12th century commentaries on this work were written by Christian scholars including Hisdosus and philosophers of the Chartres School, such as Thierry of Chartres and William of Conches. Interpreting it in the light of the Christian faith, the academics in the School of Chartres understood the dialogue to refer to creation ex nihilo.