During the Warring States period, Confucianism and Mohism together were known as the prominent schools.
Tips
history
The term 显学 originates with the Legalist philosopher 韩非 (280-233 BCE), who in 《韩非子·显学》 famously named Confucianism 儒 and Mohism 墨 as the two 显学 of the Warring States, the dominant intellectual movements of the day.
memory
显 ('to manifest / be conspicuous') + 学 ('learning / school of thought') = 'visible learning' = the school everyone is talking about. Modern usage extends from ancient philosophy to any hot academic topic.