noun
German loanword used in philosophical, literary, or academic contexts to refer to spirit, mind, or the intellectual climate of an era. Less common in everyday speech.
from German Geist
ヘーゲル哲学では、ガイストは歴史を動かす根本原理とされる。
In Hegelian philosophy, Geist is considered the fundamental principle driving history.
To understand the spirit of that era, reading the literature of the time is best.