追本溯源

to trace sth back to its origin

to sculpt / to carve / musical instrument (old)

to chase / to pursue / to look into / to investigate / to reminisce / to recall / to court (one's beloved) / to binge-watch (a TV drama) / retroactively / posthumously

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