The arts would lie open for ever to caprice and casualty, if those who are to judge of their excellencies had no settled principles by which they are to regulate their decisions, and the merit or defect of performances were to be determined by unguided fancy. And indeed we may venture to assert, that whatever speculative knowledge is necessary to the artist, is equally and indispensably necessary to the connoisseur. The first idea that occurs in the consideration of what is fixed in art, or in taste, is that presiding principle of which I have so frequently spoken in former discourses,--the general idea of nature. The beginning, the middle, and the end of everything that is valuable in taste, is comprised in the knowledge of what is truly nature; for whatever notions are not conformable to those of nature, or universal opinion, must be considered as more or less capricious. My notion of nature comprehends not only the forms which nature produces, but also the nature and internal fabric and organisation, as I may call it, of the human mind and imagination. The terms beauty, or nature, which are general ideas, are but different modes of expressing the same thing, whether we apply these terms to statues, poetry, or pictures. Deformity is not nature, but an accidental deviation from her accustomed practice. This general idea, therefore, ought to be called Nature; and nothing else, correctly speaking, has a right to that name. But we are sure so far from speaking, in common conversation, with any such accuracy, that, on the contrary, when we criticise Rembrandt and other Dutch painters, who introduced into their historical pictures exact representations of individual objects with all their imperfections, we say--Though it is not in a good taste, yet it is nature. This misapplication of terms must be very often perplexing to the young student. Is not art, he may say, an imitation of nature? Must he not, therefore, who imitates her with the greatest fidelity be the best artist? By this mode of reasoning Rembrandt has a higher place than Raffaelle. But a very little reflection will serve to show us that these particularities cannot be nature; for how can that be the nature of man, in which no two individuals are the same? It plainly appears, that as a work is conducted under the influence of general ideas, or partial, it is principally to be considered as the effect of a good or a bad taste.