Language Point 53

Descartes had unsuccessfully searched for certainty, first in the world of books, and then in the world of men. (Para. 6)
Meaning: Descartes had been not successful in searching for life with no doubt to it; he first searched for it in piles of books and then from crowds of people.
search for: try to find; look for
They searched for the missing boy everywhere, but they could not find him.

他们到处寻找那个走失了的小孩，但仍没能找到。
Scientists searched for the cause of the disease.

科学家们千方百计寻找这种疾病的病因。
We often waste our time searching for keys, glasses and other small objects that are in continuous use.

我们常常浪费时间去找那些常用的东西，如钥匙、眼镜和其他小东西。
certainty: n. the fact, quality, or state of being certain
I have told them with absolute certainty there'll be no change.

我明白无误地告诉他们不会有什么变化。
There is little certainty about the present state of the US economy.

目前美国的经济状况有许多不定的因素。