much that is intrinsic in man is like the oyster, that is loathsome and slippery and hard to grasp — so that a noble shell with noble embellishments must intercede for it.
Nietzsche uses the oyster as a figure for the repellent and elusive interior of the human psyche, arguing that a constructed outer form — the noble shell — is a necessary mediation for what is difficult and unpalatable within.
, Thus Spoke Zarathustra, 1883thesis