"In a Glass-House, the Workmen often fling in a small quantity of fresh Coals, which seems to disturb the Fire, but very much enlivens it. This seems to allude to a gentle stirring of the Passions, that the Mind may not languish."
— Swift, Jonathan (1667-1745)
Written in 1706. See also 1726 and later publications under the title Thoughts on Various Subjects, which expands the original publication. Modernized text consulted at Project Gutenberg.