ray of light
Idiomatic expression often used figuratively for a glimmer of hope or a small positive sign in a difficult situation.
暗いニュースの中で、彼の回復は一条の光だった。
Amid the dark news, his recovery was a ray of light.
Composed of 一条 (one streak) and 光 (light), literally 'a single streak of light'. The figurative use as a glimmer of hope is a natural extension.