Traces the development of the idea of experience (Greek peira, empeiria) in Greek thought, from its origins in the Presocratics, through Aristotle and subsequent Peripatetics (Theophrastus, Alexander of Aphrodisias), to Galen. Particular emphasis is placed on the ideas of the medical school of the Empirics, who based their theory and practice on experience and memory. This experience-based epistemology can be traced back to the “epistemic modesty” characteristic of Archaic Greek thought. Some passages in Avicenna, redolent of Sufism, which react to perceived shortcomings in the Aristotelian theory of cognition and demonstration (especially the ineffability of individuals) may have been influenced by the medical Empirist tradition. This emphasis on experience, shared by Archaic Greek thought, medical Empirism, and by certain aspects of Buddhism, may have influenced Islamic Sufism, and hence the thought of Avicenna and his successors.