This study is the first volume in the new Philo of Alexandria Commentary Series. It contains a new English translation of Philo's famous treatise "On the creation of the cosmos" (the first for seventy years), and the first ever commentary in English. In this work the Jewish exegete and philosopher gives a selective exegesis of the Mosaic creation account and the events in Paradise as recorded in Genesis 1-3. It is the first preserved example of Hexaemeral literature, and had a profound influence on early Christian thought. The commentary aims to make Philo's thought accessible to readers such as graduate students who are just beginning to read him, but also contains much material that will be of interest to specialists in Hellenistic Judaism, ancient philosophy and patristic literature.