When the mind has put off the old self and shall put on the one born of grace, then it will see its own state in the time of prayer resembling sapphire or the color of heaven; this state scripture calls the place of God that was seen by the elders on Mount Sinai.!’ — EVAGRIUS OF PONTUS
The world is blue at its edges and in its depths. This blue is the light that got lost. Light at the blue end of the spectrum does not travel the whole distance from the sun to us. It disperses among the molecules of the air, it scatters in water. Water is colorless, shallow water appears to be the color of whatever lies underneath it, but deep water is full of this unscattered light, the purer the water the deeper the blue. The sky is blue for the same reason, but the blue at the horizon, the blue of land that seems to be dissolving into the sky, is a deeper, dreamier, mlancholy blue, the bluc at the farthest reaches of the places where you see for miles, the blue of distance. This light that does not touch us, does not travel the whole distance, the light that gets lost, gives us the beauty of the world, so much of which is in the color blue. — REBECCA SOLNIT
(Quoted in The Blue Sapphire of the Mind by Douglas E. Christie)