The title “All Things Are in Flux” sounds like Heraclitus’ panta rhei (“everything flows”). Mihawk’s answer pairs it with the one thing that does not flow, a sense of self.
Japanese title:万物は変わりゆく (Banbutsu wa Kawariyuku, “all things go on changing”). The standard Japanese name for Heraclitus’ doctrine is 万物流転 / 万物は流転する (banbutsu wa ruten suru), and English calls it the doctrine of flux. Oda’s title shares the subject 万物 “all things”, and VIZ’s English shares the word “flux”, so the echo holds in both languages. Oda uses the plain verb 変わりゆく, not the philosophical 流転, so the citation stays an allusion and is not a quotation. Confidence: medium.
The Haki side of the riddle: 覇気 haki means “ambition / domineering will”, and 覇王色 haōshoku means “Supreme King type”. The One Piece Wiki already records Supreme King Haki as “impossible to awaken through training”, which Mihawk’s “not learned through discipline” (p.11) now puts in a character’s mouth. Unresolved: the Japanese word behind VIZ’s “a sense of self” (自我? 我?) was not found in any source checked, so no gloss is offered.
Sources: One Piece Wiki: Chapter 1194 · Wikipedia: Heraclitus § Panta rhei · ja.wikipedia: 万物流転 · One Piece Wiki: Supreme King Haki.
Whether Mihawk himself has Supreme King Haki is NOT stated on-page. He teaches it; he does not claim it.
The payoff
(Pending. Forward of 1194.)
Why this matters
Oda states the rule (Supreme King Haki = an unchanging self, not trained technique) in the same chapter that shows it surfacing. The payoff is on a short fuse. It also re-reads Zoro’s earlier involuntary flashes (@1010, @1152) as a selfhood problem rather than a training gap.