Theodor Schreiber (1848 - 1912) was a classical archaeologist, art historian, and monument protector. His lasting significance in art history stems from his work on Hellenistic monuments, where he sought to highlight the particular contribution of Ptolemaic-Alexandrian art to Hellenistic art and culture. Criticized during his time, many of his theories have been proven correct by recent research. The present habilitation thesis is dedicated to the myth of Apollo's battle with the dragon Python and provides a comprehensive overview of the tradition and source material related to the topic. Reprint of the original edition from 1879.