The use of concrete symbols or images is the most widespread of these primitive modes of thought. It is natural that the more complex should at the first be described in terms of the less complex, that those experiences for which no proper terminology has been hammered out should be given names out of man’s existing vocabulary. That is inevitable: but there is an even more fundamental process at work. It seems as if the human mind works, on its most primitive levels, by means of image-formation, and that emotions and concepts for which no simple image exist may call up symbolic images by association and indeed often dress themselves in these new clothes before they present themselves to consciousness. Some such process appears to take place in dreams (including day-dreams!) and possibly in the ordinary thought-processes of savages. More advanced modes of thought substitute the currency of an arbitrary token such as a word or a formula for the barter of images and concrete symbols; the freshness and vividness of the image is lost, but more efficient and speedier working is attained. However, in most of us the concrete image-using mode of thought is a relief from the apparently less natural and more artificial (though more efficient) operations of reason, and we relapse into it, wholly or partially, more often than we realize. This unconscious irrational tendency to symbolism, together with the other tendency to project ideas properly attaching to the subjective world into external objects and processes--these between them account for much of the modes of expression so far found for religious belief; and, since the majority of human beings have a profound distaste for sustained or difficult thought, it is likely that they will continue to account for much in the future.