Quote Originally Posted by oldboy View Post
I understand it )) I said it incorrectly.
I meant what does the listener knows about that day: that there was a party at Jane's party or that the author was babysitting?
The person who is listening... they know the date of Jane's party but not that the speaker had to babysit on that same day. Once the speaker tells them that it is the same date, then the listener knows that both events happened on the same day.