"There's a law of diminishing returns on preaching". So said author Kate Grenville in a thought provoking lecture, 'Writers in a Time of Change', in 2009*. Yet everyday, in thousands of blog posts and columns all over the world, preaching is exactly what many very earnest writers do. I do it myself - often. There is lots that's wrong in our world and writers, particularly non-fiction writers, feel obliged to point these things out. Serious points, we believe, require serious treatment. The better writing avoids the rant.