Turning those pages and studying their photographs is like flowing on a sad current that, like Blake's Thames, seems to "mark in every face, marks of weakness, marks of woe." (Para. 32)
Meaning: Moving those pages one by one and studying their photographs is something similar to moving on a sad current. The current, like the English poet William Blake's Thames, seems to leave marks of weakness and marks of great sadness in every human's face.
current: n. a continuous flowing movement of water, air, etc.
Be careful as this wire carries electrical current. 小心，這電線有電。
Strong water currents can be dangerous to swimmers. 急流對游泳者來說是危險的。
current: a. from or about the present time
Because of developments in international communication, current news is at hand almost everywhere. 由于國際通訊的發展，到處都可以收到時事新聞。
Current directions in military science place great importance on defense networks. 現代軍事科學的趨勢是注重防衛系統。