1. What Eignung is to artifacts and acorns, Ereignis is to ex-sistence – but with an important twist.
Ereignis does have to do with κίνησις, and κίνησις does have to do with incompleteness
However, Ereignis applies exclusively to existential κίνησις.
2. Ex-sistence is unique in being already “complete” in its incompleteness, already “whole” as never being whole.
Ex-sistence is perfectly “perfect” in its imperfection, its inability to achieve complete self-coincidence.
In SZ, what accounted for ex-sistence’s finitude (its open-ended-ness vs. full selfpresence) was called “thrownness.” But in 1936 Heidegger began calling thrownness “Er-eignis” (“ap-propri-ation”), a term modeled on Eignung.
3. Appropriation names the fact that ex-sistence has been brought a priori into its proper ownness (er-eignet) as the finite, mortal Open (GA 73,1: 226.26; GA 12: 128.29-30.; 248.16; 249.5–6).
The word “Ereignis” simply reinscribes the basic structure of ex-sistence that SZ had called thrownness. (GA 65:34.8–9; 239.5; 252.23–25; 322.7–8 with SZ 325.37; GA 9: 377, note d; GA 73, 1: 642.28-29; etc.)
Appropriated ex-sistence is Zu-sein: as possibility, ex-sistence is in the condition of ever-becoming.
To name this asymptotic condition of ex-sistence, Heidegger adopted Heraclitus’ hapax legomenon ̓Αγχιβασίη, “ever approaching” (fragment 122).
4. Appropriation is not an “event” in any sense of that term (GA 14: 25.33; GA 11: 45.19-20; GA 70.1719). It is an existential fact, the very facticity of ex-sistence.