The ploughman homeward plods his weary way
And leaves the world to darkness and to me
THOMAS GRAY 1751
PENUMBRA: An Imperfect Shadow
The partial shaded region around the shadow of an opaque body;
the partial shadow as distinguished from the total shadow or umbra.
Oxford English Dictionary 1971
The shadow consists of two parts; the umbra or total shadow, a cone
into which no direct sunlight penetrates, and the penumbra or half
shadow which is reached by light from only a part of the sun’s disk.
Encyclopaedia Britannica 1957
What is your substance, whereof are you made,
That millions of strange shadows on you tend?
Since every one hath, every one, one shade,
And you, but one, can every Shadow Lend.
WILLIAM SHAKESPEARE 1609