This same picture will furnish us with another instance, where we must depart from nature for a greater advantage. The Moon in this picture does not preserve so great a superiority in regard to its lightness over the subject which it illumines as it does in nature; this is likewise an intended deviation, and for the same reason. If Rubens had preserved the same scale of gradation of light between the Moon and the objects which is found in nature, the picture must have consisted of one small spot of light only, and at a little distance from the picture nothing but this spot would have been seen. It may be said, indeed, that this being the case, it is a subject that ought not to be painted; but then, for the same reason, neither armour, nor anything shining, ought ever to be painted; for though pure white is used in order to represent the greatest light of shining objects, it will not in the picture preserve the same superiority over flesh as it has in nature, without keeping that flesh colour of a very low tint. Rembrandt, who thought it of more consequence to paint light than the objects that are seen by it, has done this in a picture of Achilles which I have. The head is kept down to a very low tint, in order to preserve this due gradation and distinction between the armour and the face; the consequence of which is, that, upon the whole, the picture is too black. Surely too much is sacrificed here to this narrow conception of nature; allowing the contrary conduct a fault, yet it must be acknowledged a less fault than making a picture so dark that it cannot be seen without a peculiar light, and then with difficulty. The merit or demerit of the different conduct of Rubens and Rembrandt in those instances which I have given, is not to be determined by the narrow principles of nature, separated from its effect on the human mind. Reason and common-sense tell us, that before, and above all other considerations, it is necessary that the work should be seen, not only without difficulty or inconvenience, but with pleasure and satisfaction; and every obstacle which stands in the way of this pleasure and convenience must be removed. The tendency of this Discourse, with the instances which have been given, is not so much to place the Artist above rules, as to teach him their reason; to prevent him from entertaining a narrow, confined conception of Art; to clear his mind from a perplexed variety of rules and their exceptions, by directing his attention to an intimate acquaintance with the passions and affections of the mind, from which all rules arise, and to which they are all referable. Art effects its purpose by their means; an accurate knowledge, therefore, of those passions and dispositions of the mind is necessary to him who desires to affect them upon sure and solid principles.