Any movement is like this — when it concludes, it is vast.
Tips
history
From 《庄子·人间世》: 其作始也简,其将毕也必巨。(Its beginnings are modest; its ending must be enormous.) Zhuangzi warns Yan Hui about the inflation of consequences: small ideological projects tend to balloon into unmanageable ones. Mao Zedong quoted the couplet in 1956 at the 8th CCP Congress to justify his revolutionary ambitions.
usage
Always paired with 其作始也简. 也 is a classical pause particle. 将 here means 'about to / going to' (jiāng), not 'general' (jiàng). The couplet's tone can be either triumphal or cautionary depending on context.