Once upon a noontime dreary, while I pondered, weak and weary,
Wall of the Chamber under Window covered,
the Cloth involved, Darkness reflected,
The Sun shining in the Chamber door.
For when I was trying, a Friendly visit,
I stopp'd him at the shaded Door,
and before I told him what the Colours were,
Colours mix'd again; white Light as before.
Provided the Light be not so far diminished,
but that the Colours be sufficiently visible,
blues and violets refrange somewhat more,
in rain-bows from sun-lighted door.
Obviously my mind is staying focused...