An exhaustive study of this generic aspect of value lies, of course, outside the scope of this book. Ehrenfels, Meinong, and others,[120] have made fruitful investigations in the psychology of value, with primary reference to the problems of ethical value, while Gabriel Tarde, approaching the subject with a sociological, rather than psychological or ethical interest, has also made some illuminating suggestions. The most comprehensive work in English, from the psychological point of view, is by Professor W. M. Urban, whose _Valuation_ appeared in 1909. His interest is also chiefly in ethical, rather than economic, value. Reference has been made in an earlier footnote[121] to Simmel's views. There is, in fact, a rich literature on the subject. The theory of economic value to be developed in this volume, however, is relatively independent of many of the theories treated in this literature, since, as will appear later, the question I wish to raise is, not so much as to the fundamental nature of value, in its psychological aspects, but rather, as to _what_ individual values (and in what _relations_) are significant for the explanation of the particular sort of value with which the economist is concerned. The exposition which follows will be clearer, however, if a psychological theory of value be premised, and the discussion of social economic value will gain from a consideration of ethical and other forms of value, in their sociological aspects, as treated by some of the writers named. The rest of this chapter will be concerned with the problem of value as it presents itself in individual psychology, and later chapters will treat the problem of social value. _For_ the experience, and at the time of the experience, a value is a _quality_ of the object valued.[122] Values are "tertiary qualities" (to borrow an expression from Professor Santayana's _Life of Reason_[123]), just as real and objective as the "primary" and "secondary" qualities. We speak of a gloomy day, or a fearful sight, and the gloom is a quality of the day, and the fearfulness is really in the object--for the experience. When we have sufficiently reflected upon the situation to be able to separate subject and object, and to divest the object of the quality, and put the fear in ourselves, or the gloom in our own emotional life, then the experience is already past, and the value, as the value of that object, has ceased to be. We are already over our fear when we can separate it from the object. These qualities are intensive qualities, may be greater or less in degree, i.e., are quantities.[124] And they must first _exist_, as such quantities, before any reflective process of evaluation and comparison can put them in a scale, and make clear their _relative_ values.[125]