Date: 1686, 1689, 1697

"The grand Instruments by which the Understanding works, are Memory and Invention: Now, since these Faculties have their foundation in the sensitive Capacity, as this Prop is withdrawn, the Understanding must of Consequence be more clouded and obscure."

— Nourse, Timothy (c.1636–1699)

Date: September 10, 1836

"And the blue sky in which the private earth is buried, the sky with its eternal calm, and full of everlasting orbs, is the type of Reason."

— Emerson, Ralph Waldo (1803-1882)

Date: 1901-2, 1902

"It is to be hoped that we all have some friend, perhaps more often feminine than masculine, and young than old, whose soul is of this sky-blue tint, whose affinities are rather with flowers and birds and all enchanting innocencies than with dark human passions, who can think no ill of man or God...

— James, William (1842-1910)