expression, godan verb (-u)
leave home to study; carry a case of books
Rare idiomatic expression. Literally means 'to carry a case of books on one's back', figuratively used for leaving one's hometown to pursue study. The literal sense is historical; the figurative sense is the main modern usage.
若い頃、彼は笈を負って都へ出た。
When he was young, he left his hometown carrying his books and went to the capital to study.
The expression '笈を負う' is hardly used nowadays.