This dissertation investigates the relationship between the plays of Sophocles and the philosophy of the pre-Socratics. The question considered is whether or not Sophocles' tragedies were influenced by pre-Socratic thought in distinction from Sophistic thought. Scholars generally have recognized the impact of the Sophists on Sophoclean tragedy and determined it to be evidence of Sophocles' primarily negative dramatic treatment of so-called 'Enlightenment' thought of the 5th century B.C.E. This study determines the presence of pre-Socratic thought in the tragedies of Sophocles and views its influence as a primarily positive instance of 5th century 'Enlightenment' thought in these plays, in contrast to the general depiction of Sophistic thought. Three works of Sophocles' extant plays are examined in separate chapters. A chapter on Sophocles' Philoctetes elucidates traces of the philosophy of Heraclitus in this tragedy. Sophocles deploys certain Heraclitean images in the character portrayal of Philoctetes, whose moral outlook contrasts with the Sophistic vision of Odysseus. A second chapter, on the Trachiniae, argues that this tragedy recalls the philosophy of Heraclitus, as well as 'Enlightenment' thought of the Ionian scientific tradition in general. This evidence is significant to the construction of the various images, themes, and character portrayals in this tragedy. Lastly, in a third chapter, on the Antigone, the pre-Socratic views of Heraclitus, Xenophanes, and Anaximander, as well as ideas of the pre-Socratics in general, are instrumental in defining the character of Antigone, who adheres to a pre-Socratic vision of nature, law, and justice, and conflicts with Creon, who embraces the Sophistic praise of man's conquest of nature and the severance of nature from law, justice, and the gods. Two opposing philosophical systems, pre-Socratic philosophy (which also ultimately defines the views of Haemon and Teiresias) and the ideas of the Sophists, are essential to defining the conflict between the characters in the Antigone. This dissertation concludes that pre-Socratic philosophy influences the creation of Sophocles' plays, both thematically and with respect to character portrayal; and that Sophocles' dramatic representation of pre-Socratic thought serves as an example of his positive reception of 'Enlightenment' thought.