to study diligently under extremely poor conditions, based on the legends of one student collecting fireflies in a bag for light and another reading by the reflection of moonlight on snow

To study diligently despite living in poverty; refers to the story of Sun Kang from the Jin Dynasty who used the reflection of snow at night to read because he was too poor to afford lamp oil

to study by the light of reflected snow or a bag of fireflies; an idiom describing extreme diligence in one's studies despite poverty

(idiom) to study hard despite difficult circumstances; literally to use the light from fireflies and the reflection from snow to read

(idiom) to study diligently despite poverty or harsh conditions; literally "to collect fireflies and study by the reflection of snow"