It's often put in terms of the relationship between the part and the whole. I approach a text and of course the first thing I read is a phrase or a sentence.

经常可以理解为,局部和整体的关系，我看到文本后,首先读到的东西理所当然是一个短语或一个句子。

耶鲁公开课 - 文学理论导论课程节选

So, the first thing we do is put two electrons between h and c, and then two electrons between c and n.

那么，我们先在氢和碳之间放两个电子，然后在碳和氮之间再放两个电子。

麻省理工公开课 - 化学原理课程节选

Here's the key paragraph from the statement that the Bank put out first thing this morning.

BBC: Swiss move to make its safe-haven less attractive

We didn't think that was the right sort of thing to put in there at first until we'd debugged it.

ENGADGET: Backstage at the Google press conference

O'NEILL: The president said from the very beginning in all that we do we should put compassion first and it's a compassionate thing to recognize that people may have a longer duration of unemployment.

CNN: Treasury Secretary Paul O'Neill