Heraclitus repeatedly uses the "open mystery" formula to determine nature and to characterize the dialectics of explicit and implicit.
Nature is a unity of contradictions, which are, firstly, the contradictions of nature itself, being itself, and secondly, the contradictions of knowledge. Nature and human knowledge are in a deep relationship, which can be understood through vision - this is the correspondence of the visible and the seeing, light (sun) and eye.
