I'd concur with those who have noted the impossibility of packing a densely scripted novel into the limits of a typical length movie. But conversely there is a class of film which plays to the medium's *strengths in ways that no book can, er, replicate. I am thinking of course of the stunning visual impact (which continues to affect visual design and architecture to this day) of a film like Ridley Scott's Blade Runner - the little story of 'Do Androids Dream...' is surely of limited interest and consequence by comparison.