自生自灭 is formed by duplicating the reflexive pronoun 自 (self) and pairing it with two antithetical verbs: 生 (to live/born) and 灭 (to perish/extinguish), creating a compound where the first half 自生 means "to arise by itself" and the second half 自灭 means "to die out by itself", combined to express the concept of spontaneous emergence and disappearance without external intervention.