This study focuses on the role played by Presocratic thinkers in the work of the physician-cum-philosopher Galen of Pergamum (129–c. 216 CE). It starts from Galen’s attitude towards the intellectual past. For Galen too Socrates marks a turning point but only in so far as he called for a teleological approach to the study of nature and inspired Plato in taking such an approach in the Timaeus. Before Plato however Hippocrates had laid the foundations of natural philosophy and medicine by propounding the theory of the four elements (further analysable into the principles of matter and elementary quality) and refuting the material monism of the Ionian cosmologists as well as Eleatics, most notably Melissus. Yet the watershed is less strict than it might appear at first blush: Galen traces back unarticulated and partial expressions of the true view of nature to thinkers before Hippocrates such as Melissus, Empedocles and Heraclitus. Anaxagoras plays an analogous but negative role, viz. as a precursor of materialism and scepticism. Galen’s approach to these Presocratics bears the stamp of Aristotle, Theophrastus and the later doxographic tradition. This tradition also provided him with diaeretic schemas of options—including those associated with Presocratics—which served him as a dialectical tool for organizing his discussions. In ethics Galen associates Pythagoras with Socrates as a moral beacon. He refers to Heraclitus and Pythagoras as being on the right track and anticipating Plato concerning the nature and the structure of the soul respectively.