Because film operates in real time, it is more limited. Novels end only when they feel like it. Film is, in general, restricted to what Shakespeare called "the short two hours' traffic of our stage." Popular novels have been a vast reservoir of material for commercial films over the years.... But commercial film still can't reproduce the range of the novel in time. An average screenplay, for example, is 125 to 150 pages in length; the average novel twice that. Almost invariably, details of incident are lost in the translation from book to film.