movie theater is the best place to verify the theories which we are here trying to explain in words. Go to the movies. Whenever you find that you enjoy the films thoroughly, then by all means do not stop to analyze or criticise. If you enjoy any particular film so much that you are sure you would like to see it two or three times every year for the rest of your life, you may be happy, for you have discovered one of the classics of the screen. Do not analyze that film either, unless you are in the business of making pictures. But if a film makes you uncomfortable, or if it is so bad that you are quite disgusted with it, then, though you must become a martyr to do it, please stay and see it again. Compare the good parts of the film, if there are any, with the bad parts; study it in detail until you see where the trouble lies. And when you have discovered the real causes of ugliness in that film, wouldn't it be a public service to express your opinion in such a way that the manager of your theater might hear it?
Thus far in this chapter we have discussed only a single operation of the eye, namely, the expanding and contracting of the pupils under the effect of darkness and brightness, but it is easy to understand now how such an apparently slight thing may seriously affect our enjoyment of the movies. Let the reader, when he is next displeased by a picture, test it for sharpness of contrast between white and black. He will probably not have to seek further for explanation of its ugliness.
Another operation which the eye-machine performs is the accommodation to color. It is somewhat similar to the accommodation to distance, which we shall de-
