Indirect object-me
Direct object-an invitation
Preposition-to
I believe a motif can contribute to, or become a theme when it gathers larger significance throughout a text. A theme is what you generally write about in a literary piece, so if you develop a metaphor further, it may come to denote a theme of a work.
<span>"three men in a boat" is a humorous account by jerome k jerome of a boating holiday on the thames between Kingston and oxford. The book was initially intended to be a serious travel guide with accounts of local history but the humorous took over the point.</span>