"The more you examine properties of objects and phenomena the more you find yourself presented with a few terms, usually simple, from a long series of terms. Often you cannot touch the terms which are further or lower in the series, but you can define the properties which they have. One gets the feeling of living in a container—one of an infinite number—to which are shunted objects and phenomena which have passed through one filter but can't pass through another; a great process like that which takes place in a gravel yard, only we are unable to see gravel other than that of our own size but sense that it exists in endless different piles beyond—everything from sand to planet sized boulders."