Solid, opaque things cast shadows.  Our presence is not confined to the solid and defined outline of our body.  Our presence spreads out, casting a shadow and providing shade.

That’s the phenomenological basis behind the Bible’s use of shade/shadow imagery.  Shadows symbolize protection.  Lot invites the angels to enter the “shadow” of his house (Gen 19:8), we come under the shadow of the Lord’s wings, kings are trees or rocks in whose shadow people find refreshment (ironically in Judges 9:15), and so are lovers (Song of Songs 2:3) and so is money (Ecclesiastes 7:12).  Our shadows pass away; paradoxically, like a shadow at sundown, our presence lengthens and reaches its fullest extent just before it goes out entirely (cf. Psalm 109:23).  Shadows and shade thus also become symbolic of the brevity of life.  Only Yahweh’s shade is permanent.