If, however, I shall have frequent occasion to insist on the necessity of this heartfelt love of, and unqualified submission to, the teaching of nature, it will be no less incumbent upon me to reprobate the careless rendering of casual impression, and the mechanical copyism of unimportant subject, which are too frequently visible in our modern school.[O] Their lightness and desultoriness of intention, their meaningless multiplication of unstudied composition, and their want of definiteness and loftiness of aim, bring discredit on their whole system of study, and encourage in the critic the unhappy prejudice that the field and the hill-side are less fit places of study than the gallery and the garret. Not every casual idea caught from the flight of a shower or the fall of a sunbeam, not every glowing fragment of harvest light, nor every flickering dream of copsewood coolness, is to be given to the world as it came, unconsidered, incomplete, and forgotten by the artist as soon as it has left his easel. That only should be considered a picture, in which the spirit, (not the materials, observe,) but the animating emotion of many such studies is concentrated, and exhibited by the aid of long-studied, painfully-chosen forms; idealized in the right sense of the word, not by audacious liberty of that faculty of degrading God's works which man calls his "imagination," but by perfect assertion of entire knowledge of every part and character and function of the object, and in which the details are completed to the last line compatible with the dignity and simplicity of the whole, wrought out with that noblest industry which concentrates profusion into point, and transforms accumulation into structure; neither must this labor be bestowed on every subject which appears to afford a capability of good, but on chosen subjects in which nature has prepared to the artist's hand the purest sources of the impression he would convey. These may be humble in their order, but they must be perfect of their kind. There is a perfection of the hedgerow and cottage, as well as of the forest and the palace, and more ideality in a great artist's selection and treatment of roadside weeds and brook-worn pebbles, than in all the struggling caricature of the meaner mind which heaps its foreground with colossal columns, and heaves impossible mountains into the encumbered sky. Finally, these chosen subjects must not be in any way repetitions of one another, but each founded on a new idea, and developing a totally distinct train of thought; so that the work of the artist's life should form a consistent series of essays, rising through the scale of creation from the humblest scenery to the most exalted; each picture being a necessary link in the chain, based on what preceded, introducing to what is to follow, and all, in their lovely system, exhibiting and drawing closer the bonds of nature to the human heart. Since, then, I shall have to reprobate the absence of study in the moderns nearly as much as its false direction in the ancients, my task will naturally divide itself into three portions. In the first, I shall endeavor to investigate and arrange the facts of nature with scientific accuracy; showing as I proceed, by what total neglect of the very first base and groundwork of their art the idealities of some among the old masters are produced. This foundation once securely laid, I shall proceed, in the second portion of the work, to analyze and demonstrate the nature of the emotions of the Beautiful and Sublime; to examine the particular characters of every kind of scenery, and to bring to light, as far as may be in my power, that faultless, ceaseless, inconceivable, inexhaustible loveliness, which God has stamped upon all things, if man will only receive them as He gives them. Finally, I shall endeavor to trace the operation of all this on the hearts and minds of men; to exhibit the moral function and end of art, to prove the share which it ought to have in the thoughts, and influence on the lives of all of us; to attach to the artist the responsibility of a preacher, and to kindle in the general mind that regard which such an office must demand.