Where the shape comes from
A nose seen face-on, the bridge and the flare of both nostrils drawn in a few strokes — and, because pointing at one’s own nose was the ordinary gesture for myself, the character drifted entirely into meaning self, from, since, leaving 鼻 to be built afresh once 自 no longer read as a nose to most readers. Breath felt from the nose down to the heart gives 息, to breathe, to rest; and it names the self plainly in 自己, oneself.
汉字 filed under 自
No published character on HSK Guide is filed under this radical yet. 汉字库.