It is in general to be observed, first, that this kind of sculpture admits not indifferently of every attitude and action; as for instance, of too strong projections of the legs. Secondly, That, besides disposing of the several modelled figures in well-ranged groupes, the diameter of every one ought to be applied to the bas-relief itself, by a lessened scale: as for instance, the diameter of a figure in the model being one foot, the profile of the same, according to its size, will be three inches, or less: the rounder a figure of that diameter, the greater the skill. Commonly the relief wants perspective, and thence arise most of its faults. Though I proposed to make only a few remarks on the ancient bas-relief, I find myself, like a certain ancient Rhetor, almost under a necessity of being new-tuned. I have strayed beyond my limits; though at the same time I remembered that there is a law among commentators, to content themselves with bare remarks on the contents of a treatise: and also sensible that I am writing a letter, not a book, I consider that I may draw some instructions for my own use, ——_ut vineta egomet cædam mea,_ Hor. from some peoples impetuosity against the author; who, because they are hired for it, seem to think that writing is confined to them alone. The Romans, though they worshipped the deity Terminus (the guardian God of limits and borders in general; and, if it please these gentlemen, of the limits in arts and sciences too), allowed nevertheless an universal unrestrained criticism: and the decisions of some Greeks and Romans, in matters of an art, which they did not practise, seem nevertheless authentick to our artists. Nor can I find, that the keeper of the temple of peace at Rome, though possessed of the register of the pictures there, pretended to monopolize remarks and criticisms upon them; Pliny having described most of them. _Publica materies privati juris sit_— Hor. ’Tis to be wished, that, roused by a Pamphilus and an Apelles, artists would take up the pen themselves, in order to discover the mysteries of the art to those that know how to use them, _Ma di costor’, che à lavorar s’accingono,_ _Quattro quinti, per Dio, non sanno leggere._ Salvator Rosa, Sat. III. Two or three of these are to be commended; the rest contented themselves with giving some historical accounts of the fraternity. But what could appear more auspicious to the improvement of the art, even by the remotest posterity, than the work attempted by the united forces of the celebrated Pietro da Cortona[42] and Padre Ottonelli? Nevertheless this same treatise, except only a few historical remarks, and these too to be met with in an hundred books, seems good for nothing, but _Ne scombris tunicæ desint, piperique cuculli._ Sectan. Sat. How trivial, how mean are the great _Poussin_’s reflexions on painting, published by Bellori, and annexed to his life of that artist[43]?