 Of particular note are some sayings attributed to the Ionian philosopher Heraclitus (fl. ca. 500 BCE). One fragment reads, “The things of which there is sight, hearing, experience, [these] I prefer” (DK 22B55; Graham 2010: 149). Although the contrast here may be between knowledge by experience and knowledge by hearsay (Kahn 1979: 106), it does suggest a confidence in knowledge of the former kind. It is, however, balanced by another saying, which notes that “poor witnesses for men are the eyes and ears of those who have barbarian souls” (DK 22B107; Graham 2010: 149). Whereas the senses can provide knowledge, what they offer needs to be correctly understood. Empedocles (ca. 495–435 BCE), too, while emphasizing the limits of human understanding, encourages his hearers to “understand each thing in the way in which it is clear [noei d’hēi dēlon hekaston],” gleaning what knowledge they can from the senses (DK 31B3; Graham 2010: 343).