The lake lay blue below the hill.
O'er it, as I looked, there flew
Across the waters, cold and still,
A bird whose wings were palest blue.
The sky above was blue at last,
The sky beneath me blue in blue.
A moment, ere the bird had passed,
It caught his image as he flew.
This poem by Mary E Coleridge was set to music by Charles Villiers Stanford, and the song comes to mind as I contemplate the shades of blue in these iris.
Some time ago, on a certain Summer's evening, you could wander onto on the banks of the river Cam behind the colleges, and sit and wait for the arrival of a choir, seated on a raft of punts. And as the sun slowly set and darkness fell, they would sing for you ancient and modern songs, of which the above was one. And the end of the concert, in the dark, with lanterns lit, they would disappear back down the river, the only other sounds being the night insects and the splash of punt poles. Quite magical.