Full Idea
They purify themselves by staining themselves with other blood, as if one were to step into mud to wash off mud. But a man would be thought mad if any of his fellow-men should perceive him acting thus.
Gist of Idea
Purifying yourself with blood is as crazy as using mud to wash off mud
Source
Heraclitus (fragments/reports [c.500 BCE], B005), quoted by Origen - Against Celsus 7.62
Book Reference
'Ancilla to the Pre-Socratic Philosophers', ed/tr. Freeman,Kathleen [Harvard 1957], p.25