What does the idiom take his temperature mean?

The idiom "take his temperature" is a figurative expression that means to assess someone's mood or attitude. It originates from the literal act of taking someone's temperature using a thermometer to check for illness.

Here's how it's used:

* "I'm going to take his temperature before I ask for a raise." This implies that the speaker wants to gauge the boss's mood and see if it's a good time to approach him about a raise.

* "She's been really quiet all day. I need to take her temperature and see what's going on." This implies that the speaker wants to understand the person's emotional state and see if something is bothering them.

In essence, "taking someone's temperature" is about assessing their emotional state or intentions.