Most people think that shadows follow, precede, or surround beings or objects. The truth is that they also surround words, ideas, desires, deeds, impulses and memories.
— Elie Wiesel, writer, Nobel laureate (b. 1928)
There are two kinds of light — the glow that illuminates, and the glare that obscures.
— James Thurber, writer and cartoonist (1894-1961)
Shadow is the absence of light, merely the obstruction of the luminous rays by an opaque body. Shadow is of the nature of darkness. Light [on an object] is of the nature of a luminous body; one conceals and the other reveals. They are always associated and inseparable from all objects. But shadow is a more powerful agent than light, for it can impede and entirely deprive bodies of their light, while light can never entirely expel shadow from a body, that is from an opaque body.
— From the Notebooks of Leonardo da Vinci (1565, page 119)