The blue of distance

I am currently reading Rebecca Solnit's "A Field Guide to Getting Lost".  In the book the chapters alternate between memoir and philosophical musings.  The philosophical chapters are titled "The Blue of Distance".  In the first "Blue of Distance" chapter she compares medieval painting with renaissance painting.  Early medieval paintings were sometimes backed up by a solid wall of gold.  As artists became more interested in painting what the eye saw and with the emergence of perspective "they seized upon the blue of distance".  Ms. Solnit quotes Leonardo Da Vinci's advice to young painters: "To make one more distant than another, you should represent the air as more dense.  Therefore make the first building ... of its own color; the next most distant make less outlined and more blue; that which you wish to show at yet another distance, make bluer yet again; and that which is 5 times more distant make 5 times more blue."
In another section she writes: "There is no distance in childhood: for a baby, the mother in another room is gone forever, for a child the time until a birthday is endless ... Their mental landscape is like that of medieval paintings, a foreground full of vivid things and then a wall.  The blue of distance comes with time, with the discovery of melancholy, of loss, the texture of longing, of the complexity of the terrain we traverse, and with the years of travel."
The first quote is new information for me and so simple it's remarkable: blue brings distance.  The second quote is not entirely new and a bit obvious: time brings experience.  It is interesting  that  she equates time/experience with loss and melancholy.  To take her example, when the mother leaves the room the child's experience of loss often leads to loud crying which brings the mother back.  But then the child is happy again.
I was just reminded of Dylan Thomas': "Rage against the dying of the light".  Rage against the melancholy in your life!