We use the -ing adjectives to describe the thing or person that causes the feeling.
For example: The book was very interesting.
In this example the adjective (interesting) describes the thing (the book).
We use the -ed adjectives to describe the person who has the feeling, to explain how he/she feels.
For example: Mary is interested in the book.
In this example the adjective (interested) describes how the person (Mary) feels in relation to the thing (the book).
-ing adjectives can describe the feeling a person causes in other people. See the example:
- Mary is bored; she has been waiting for her uncle for about 2 hours. (Bored expresses how Mary feels.)
- Mary is boring. I don’t like going out with her because she never wants to meet new people or talk to them. (Boring describes how people feel when they are with Mary.)