How can dialogue reveal the theme of a text?

Explanation:

So theme is what the author wants the reads to know. A message/lesson. Dialogue can reveal the theme by saying the lesson. For example, if the theme was to treat others how you want to be treated then a piece of dialogue could say "Don't treat them like that!" or "If you treat them like that it's going to back to you."

I really hope this helps.

The dialogue can be a conversation with 2 or more people so they can talk about how something can be wrong or like say how this can be considered bad. So let’s say the theme was don’t judge a book by its cover
. There can be people judging someone by how they look or how something looks and then they totally didn’t expect it to be something different than what it actually was and than that can make a theme for the story.

It is usually expressed through a emoji