With respect to colouring, though it may appear at first a part of painting merely mechanical, yet it still has its rules, and those grounded upon that presiding principle which regulates both the great and the little in the study of a painter.  By this, the first effect of the picture is produced; and as this is performed the spectator, as he walks the gallery, will stop, or pass along.  To give a general air of grandeur at first view, all trifling or artful play of little lights or an attention to a variety of tints is to be avoided; a quietness and simplicity must reign over the whole work; to which a breadth of uniform and simple colour will very much contribute.  Grandeur of effect is produced by two different ways, which seem entirely opposed to each other.  One is, by reducing the colours to little more than chiaroscuro, which was often the practice of the Bolognian schools; and the other, by making the colours very distinct and forcible, such as we see in those of Rome and Florence; but still, the presiding principle of both those manners is simplicity.  Certainly, nothing can be more simple than monotony, and the distinct blue, red, and yellow colours which are seen in the draperies of the Roman and Florentine schools, though they have not that kind of harmony which is produced by a variety of broken and transparent colours, have that effect of grandeur that was intended.  Perhaps these distinct colours strike the mind more forcibly, from there not being any great union between them; as martial music, which is intended to rouse the noble passions, has its effect from the sudden and strongly marked transitions from one note to another, which that style of music requires; whilst in that which is intended to move the softer passions the notes imperceptibly melt into one another.

In the same manner as the historical painter never enters into the detail of colours, so neither does he debase his conceptions with minute attention to the discriminations of drapery.  It is the inferior style that marks the variety of stuffs.  With him, the clothing is neither woollen, nor linen, nor silk, satin, or velvet:  it is drapery; it is nothing more.  The art of disposing the foldings of the drapery make a very considerable part of the painter’s study.  To make it merely natural is a mechanical operation, to which neither genius or taste are required; whereas, it requires the nicest judgment to dispose the drapery, so that the folds have an easy communication, and gracefully follow each other, with such natural negligence as to look like the effect of chance, and at the same time show the figure under it to the utmost advantage.

Carlo Maratti was of opinion that the disposition of drapery was a more difficult art than even that of drawing the human figure; that a student might be more easily taught the latter than the former; as the rules of drapery, he said, could not be so well ascertained as those for delineating a correct form, This, perhaps, is a proof how willingly we favour our own peculiar excellence.  Carlo Maratti is said to have valued himself particularly upon his skill in this part of the art yet in him the disposition appears so artificial, that he is inferior to Raffaelle, even in that which gave him his best claim to reputation.