昔素颜
[xī sù yán]
'昔素颜' reflects a sense of nostalgia for a time when one was youthful and innocent, without makeup or any pretenses. The term '昔' (xi) implies 'long ago,' and '素颜' (su yan) suggests 'natural look.' So it evokes a pure, simple, and genuine image of youth, untouched by artifice.