“Theme has become a rather vague term in the writer’s vocabulary. ‘Poverty,’ ‘war,’ and ‘love,’ for example, are not themes; they relate to setting or genre. A true theme is not a word but a sentence – one clear sentence that expresses a story’s irreducible meaning.’’
From Robert McKee’s Story: Substance, Structure, Style, and the Principles of Screenwriting (It Books/Harper Collins, 1997).