The earliest scribes drew 自 as a nose seen face-on: a ridge tapering upward, flaring out where it meets the cheeks. In China, pointing at your own nose — not your chest — is the natural gesture for "me", and that everyday habit pulled the meaning of the character from "nose" toward "self" so strongly that a new character, 鼻, eventually had to be invented to keep the original meaning of "nose" alive.
A piece of culture
The Dao that follows itself In China, Japan and Korea alike, people point to their own nose — not their chest — when they mean "me"; the gesture is old enough that it may have helped tug this pictograph of a nose toward the meaning "self". The character also seeded one of Daoism's deepest ideas: 自然 (zìrán), literally "self-so", names the natural, spontaneous way things unfold without being forced. Laozi's Dao De Jing closes its famous chapter on the cosmic order with 道法自然 — "the Way follows what is self-so" — the philosophical root of the modern Chinese word for "nature".
Use it in a real word
自己
zìjǐ · zi6 gei2
oneself — the very word people say while pointing to their nose