事后聪明谁都会。

Anyone can be wise after the event.

因此宇宙不是必然如此的，对它的认识也是通过事后的研究才能实现。

Thus the cosmos cannot be a necessary form of existence; and so it has to be approached by a posteriori investigation.

事后聪明不难； 作事后诸葛亮容易。

It is easy to be wise after the event.

当然，也存在一些减轻因素，其中最重要的一点在于，不少错误惟有通过事后分析才能明晰。

Of course, there are mitigating factors, the most important being that many of those errors have become clear only in hindsight.

事后一目了然的在当时根本看不清。

What looks obvious in hindsight was not at all obvious at the time.