Samuel Taylor Coleridge (1831). “Aids to Reflection in the Formation of a Manly Character on the Several Grounds of Prudence, Morality, and Religion: Illustrated by Select Passages from Our Elder Divines, Especially from Archbishop Leighton”, p.16
John Ruskin (1869). “Modern Painters: pt. 6. Of leaf beauty. pt. 7. Of cloud beauty. pt. 8-9. Of ideas of relation: Of invention formal. Of invention spiritual”, p.288