Jalāl al-Dīn Rūmī (Maulana), Jelaluddin Rumi, Kabir Helminski, Andrew Harvey (2005). “The Rumi Collection: An Anthology of Translations of Mevlâna Jalâluddin Rumi”, p.53, Shambhala Publications
Attributed to Aristotle in Diogenes Laertius "The Lives and Opinions of Eminent Philosophers" translated by C. D. Yonge and Henry G. Bohn (p. 188), 1853.