Wikimedia
Wikipedia: Democritus
This encyclopedia entry surveys the life and thought of the 5th century BCE Greek philosopher Democritus, who proposed the existence of the atom.
Other
Greek Philosophy: Leucippus and Democritus
This article provides an overview of the atomistic philosophy of the pre-Socratic philosophers Leucippus and Democritus in the 5th and 4th centuries, BCE.
Stanford University
Stanford Encyclopedia of Philosophy: Empedocles
Article about the Greek philosopher Empedocles from the Stanford Encyclopedia of Philosophy. Includes a brief overview of his work and more detailed discussion of his two major works: "On Nature" and "Purifications."
Massachusetts Institute of Technology
Mit: Open Course Ware: Ancient Philosophy
Ancient Greece has bestowed much to Western philosophy. This course will acquaint the student with some of the ancient Greek contributions to the Western philosophical and scientific tradition.
Other
Atlantic Baptist: Pre Socratic Lectures: Empedocles
Lecture notes on the Pre-Socratic philosopher Empedocles from a college philosophy class. Also includes some quotations as well as discussion questions in small rectangles within the notes.