William Butler Yeats Quotes about Philosophy
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"Wisdom for the Soul: Five Millennia of Prescriptions for Spiritual Healing". Book by Larry Chang, p. 417, 2006.
"The Letters of W.B. Yeats".
William Butler Yeats (2008). “COLLECTED POEMS OF W.B. YEATS”, p.513, Simon and Schuster
William Butler Yeats (2010). “The Collected Works of W.B. Yeats Vol. III: Autobiogra”, p.98, Simon and Schuster