ABSTRACT
When aristotle fled from Athens he left his school In the hands of Theophrastus, who had been his faithful friend and follower ever since his student days with Plato. Though ten years younger than his master, Theophrastus was an old man when he assumed the leadership of the Lyceum, but he lived much longer and for more than thirty years presided with honour over the education of the pupils. Already under Aristotle he had paid special attention to the study of botany and he continued to work in this science in the spirit of his master. His two treatises on plants are to botany what Aristotle's works were to zoology. Furthermore, there is extant a "history of physics" by him, which has always been the main source of our knowledge of the ideas of the ancient natural philosophers. He also wrote a zoological work, which has been lost, but on the whole it seems to have contained nothing essentially new that is not found in Aristotle.
