Tychē is what appears as chance — occurring without apparent cause and unforeseeable in advance by the individual agent. Aristotle, in Physics II 4–6, defines τύχη as "cause by accident" (κατὰ συμβεβηκός): it is real from the standpoint of the observer but does not form an independent ontological category. The Stoics, in the spirit of determinism, go further: τύχη is not "another power" alongside providence, but the name that a local observer gives to a causal connection inaccessible to him. There are no genuine "chances" in the Stoic cosmos; there are only events whose global motivation (TERMprovidence) is not open to the particular view.

Aristot. Phys. 195b31–197b37 (the conception of αἰτία κατὰ συμβεβηκός); SVF II 965–973 (the Stoic dissolution of τύχη as an independent power); Cic. De div. II 13–15; Plut. De Stoic. rep. 1050a–c. In Marcus: Med. 2.3; 4.26; 05-08 (the well-known "the threads of your life are woven together with the whole"); 9.28; 10.5.

In 02-03 τύχη appears in the first pair of formulae and is immediately disarmed: "what comes from chance is not without TERMnature or without an interweaving with what providence orders." This is a typically Stoic move: in place of a metaphysical dualism (providence vs. chance) it offers a perspectival one (the same reality under two angles of view). For Marcus there is an additional psychological effect: what I am inclined to describe as "this happened to me by chance" should be read as "this happened to me by TERMfate" — and is therefore to be accepted (amor-fati) rather than resisted.