A diagnosis instead of a reproach. The movement of the passage is medical, not moral. Fastidiousness is named not a vice but a symptom: τοῦτο γὰρ ὀφθαλμιῶντός ἐστι — "this belongs to an inflamed eye" (ὀφθαλμιάω, to suffer in the eyes). A healthy organ does not choose its object: the eye sees all that is visible; hearing and smell stand ready (ἑτοίμην εἶναι) for all that can be heard and smelled. Preference is a mark of disease, not of refinement.
Four steps and a mill. The series runs from the senses to digestion: eye, hearing and smell, stomach, and at last διάνοια. The stomach is compared to a μύλη, a mill, "with respect to everything it was constructed to grind" (ὅσα ἀλέσουσα κατεσκεύασται). The mill is not chosen at random: it does not feed, it processes — and is defined not by taste but by construction. Cf. 10.31, where the same pair "strong stomach / bright fire" stands as the image of assimilation.
The transfer to the mind. DOGMAτὴν ὑγιαίνουσαν διάνοιαν πρὸς πάντα δεῖ τὰ συμβαίνοντα ἑτοίμην εἶναι — "a healthy mind must stand ready for everything that happens." Readiness here is the very property of the healthy eye: not courage, not resignation, but the absence of selectivity. The acceptance of fate is derived from physiology rather than from will (cf. 10.20; 10.28; 4.23).
Two examples, the second harsher than the first. The sick mind says two things: "let my little children be kept safe" and "DOGMAlet everyone praise whatever I do." Marcus sets them side by side without gradation — and there lies the sharpness. The first wish looks holy, the second is plainly vain; to the diagnostician they are of one kind, both an "eye seeking green things." Note too the diminutive τεκνία ("little children"), the same word as at 10.34, where children are called little leaves.
A return to the image. The close rounds the circle: not "you are faint-hearted," but ὀφθαλμός ἐστι τὰ χλωρὰ ζητῶν ἢ ὀδόντες τὰ ἁπαλά — "this is an eye seeking green things, or teeth seeking soft ones." Diagnosis in place of verdict: the organ is not blamed, it is treated. The governing discipline is desire, the sustaining one assent.