见微知著

jiànwēi-zhīzhù

[from one small clue one can see what is coming; from the first small beginnings one can see how things will develop] 看到微小的苗头, 就知道可能会发生显著的变化。 比喻小中见大

故圣人见微知著, 睹始知终。 --汉·袁康《越绝书》