Answer: "one and the same" or "one in the same"?

[green_grrl]

English is full of phrases that get sprinkled through conversation. We pick them up, use them, and don't think too hard about them until we have to write them down. Then we realize we're not quite sure what the exact phrase is. lauramcewan asked us about one of these: "Is it 'one and the same' or 'one in the same'?" When spoken, the phrase tends to sound like "one 'n' the same," so it is understandably confusing.

Unlike some other usage questions, there is only one right answer here. I'll illustrate with the Avengers.

Let's try the classic identity question, who is Iron Man?

Tony Stark and Iron Man are one in the same.

Tony Stark and Iron Man are one and the same.

Well, Tony Stark is inside the Iron Man armor, so it could be the first one. But Tony really sees himself as Iron Man, so it could be the second one, as well.

It's easier to see the correct answer with a different example:

Natasha Romanov and Black Widow are one in the same.

Natasha Romanov and Black Widow are one and the same.

Natasha is obviously not "inside" anything. Natasha and Black Widow are one and Natasha and Black Widow are the same.

The phrase uses repetition of the same idea stated two ways to emphasize the likeness of two things.

Using in is a common mistake. Currently, googling "one in the same" returns 295 million results while "one and the same" only returns 176 million. However, remember that for many people, correct usage and a good impression are one and the same.

Comments

[lauramcewan]

Good, my instincts were correct! Thank you!

[green_grrl]

Your instincts were better than Google! :-)