推本溯源

to go back to the source

to push / to cut / to refuse / to reject / to decline / to shirk (responsibility) / to put off / to delay / to push forward / to nominate / to elect / massage

root / stem / origin / source / this / the current / original / inherent / originally / classifier for books, periodicals, files etc

to go upstream / to trace the source

variant of 溯[su4]

to investigate the origin of sth / to trace a river upstream back to its source

root / source / origin