The value of the second term must be incorporated in the first; for the beauty of expression is as inherent in the object as that of material or form, only it accrues to that object not from the bare act of perception, but from the association with it of further processes, due to the existence of former impressions. We may conveniently use the word "expressiveness" to mean all the capacity of suggestion possessed by a thing, and the word "expression" for the aesthetic modification which that expressiveness may cause in it. Expressiveness is thus the power given by experience to any image to call up others in the mind; and this expressiveness becomes an aesthetic value, that is, becomes expression, when the value involved in the associations thus awakened are incorporated in the present object. _The associative process._ Sec. 49. The purest case in which, an expressive value could arise might seem to be that in which both terms were indifferent in themselves, and what pleased was the activity of relating them. We have such a phenomenon in mathematics, and in any riddle, puzzle, or play with symbols. But such pleasures fall without the aesthetic field in the absence of any objectification; they are pleasures of exercise, and the objects involved are not regarded as the substances in which those values inhere. We think of more or less interesting problems or calculations, but it never occurs to the mathematician to establish a hierarchy of forms according to their beauty. Only by a metaphor could he say that (a + b)2 = a2 + 2ab + b2 was a more beautiful formula than 2 + 2 = 4. Yet in proportion as such conceptions become definite and objective in the mind, they approach aesthetic values, and the use of aesthetic epithets in describing them becomes more constant and literal. The beauties of abstract music are but one step beyond such mathematical relations -- they are those relations presented in a sensible form, and constituting an imaginable object. But, as we see clearly in this last case, when the relation and not the terms constitute the object, we have, if there is beauty at all, a beauty of form, not of expression; for the more mathematical the charm of music is the more form and the less expression do we see in it. In fact, the sense of relation is here the essence of the object itself, and the activity of passing from term to term, far from taking us beyond our presentation to something extrinsic, constitutes that presentation. The pleasure of this relational activity is therefore the pleasure of conceiving a determined form, and nothing could be more thoroughly a formal beauty.