In landscapes which represent [a scene in] winter.  The mountains should not be shown blue, as we see in the mountains in the summer.  And this is proved [Footnote 5. 6.:  Per la 4_a di questo_.  It is impossible to ascertain what this quotation refers to. Questo certainly does not mean the MS. in hand, nor any other now known to us.  The same remark applies to the phrase in line 15:  per la 2_a di questo_.] in the 4th of this which says:  Among mountains seen from a great distance those will look of the bluest colour which are in themselves the darkest; hence, when the trees are stripped of their leaves, they will show a bluer tinge which will be in itself darker; therefore, when the trees have lost their leaves they will look of a gray colour, while, with their leaves, they are green, and in proportion as the green is darker than the grey hue the green will be of a bluer tinge than the gray.  Also by the 2nd of this:  The shadows of trees covered with leaves are darker than the shadows of those trees which have lost their leaves in proportion as the trees covered with leaves are denser than those without leaves—­and thus my meaning is proved.

The definition of the blue colour of the atmosphere explains why the landscape is bluer in the summer than in the winter.

462.

OF PAINTING IN A LANDSCAPE.

If the slope of a hill comes between the eye and the horizon, sloping towards the eye, while the eye is opposite the middle of the height of this slope, then that hill will increase in darkness throughout its length.  This is proved by the 7th of this which says that a tree looks darkest when it is seen from below; the proposition is verified, since this hill will, on its upper half show all its trees as much from the side which is lighted by the light of the sky, as from that which is in shade from the darkness of the earth; whence it must result that these trees are of a medium darkness.  And from this [middle] spot towards the base of the hill, these trees will be lighter by degrees by the converse of the 7th and by the said 7th:  For trees so placed, the nearer they are to the summit of the hill the darker they necessarily become.  But this darkness is not in proportion to the distance, by the 8th of this which says:  That object shows darkest which is [seen] in the clearest atmosphere; and by the 10th:  That shows darkest which stands out against a lighter background.

[Footnote:  The quotation in this passage again cannot be verified.]

463.

OF LANDSCAPES.

The colours of the shadows in mountains at a great distance take a most lovely blue, much purer than their illuminated portions.  And from this it follows that when the rock of a mountain is reddish the illuminated portions are violet (?) and the more they are lighted the more they display their proper colour.

464.

A place is most luminous when it is most remote from mountains.