I puzzled over the problem for ages before the light suddenly dawned on me.

我对这个问题冥思苦想了很然开朗。

The hole yawned before him.

洞口在他面前然而开。

However, it is sticl a long way to go, for the opening of the door of truth reguires not anly the furtler development of society and history but also the sodalist's continuous explorations.

但路漫漫其修远兮，真理之门的然洞开既需会历史进程的进一步发展，也需会主义者们的继续探索。