* The subject interesting him is Greek history.
* Greek history is an interesting subject.
* Greek history is a very interesting subject.

In the first sentence, interesting functions transitively in a non-finite sense as a participle that expresses the object him, thereby forming the grammatical equivalent of "[that is] interesting him". In the second and third sentences, interesting functions as a prepositive adjective modifying subject. An adverb (such as very or recently) or a prefix (such as un-) can