The only necessary, but this the absolutely necessary, pre-requisite to a full insight into the grounds of the beauty in the objects of sight, is--the directing of the attention to the action of those thoughts in our own mind which are not consciously distinguished. Every man may understand this, if he will but recall the state of his feelings in endeavouring to recollect a name, which he is quite sure that he remembers, though he cannot force it back into consciousness. This region of unconscious thoughts, oftentimes the more working the more indistinct they are, may, in reference to this subject, be conceived as forming an ascending scale from the most universal associations of motion with the functions and passions of life,--as when, on passing out of a crowded city into the fields on a day in June, we describe the grass and king-cups as nodding their heads and dancing in the breeze,--up to the half perceived, yet not fixable, resemblance of a form to some particular object of a diverse class, which resemblance we need only increase but a little, to destroy, or at least injure, its beauty-enhancing effect, and to make it a fantastic intrusion of the accidental and the arbitrary, and consequently a disturbance of the beautiful. This might be abundantly exemplified and illustrated from the paintings of Salvator Rosa. I am now using the term beauty in its most comprehensive sense, as including expression and artistic interest,--that is, I consider not only the living balance, but likewise all the accompaniments that even by disturbing are necessary to the renewal and continuance of the balance. And in this sense I proceed to show, that the beautiful in the object may be referred to two elements,--lines and colours; the first belonging to the shapely ('forma, formalis, formosus'), and in this, to the law, and the reason; and the second, to the lively, the free, the spontaneous, and the self-justifying. As to lines, the rectilineal are in themselves the lifeless, the determined 'ab extra', but still in immediate union with the cycloidal, which are expressive of function. The curve line is a modification of the force from without by the force from within, or the spontaneous. These are not arbitrary symbols, but the language of nature, universal and intuitive, by virtue of the law by which man is impelled to explain visible motions by imaginary causative powers analogous to his own acts, as the Dryads, Hamadryads, Naiads, &c.