The Universality of Spiritual Wisdom Imparted to the World [1] (Some quotes by saints)
A comparison of hesychasm and other traditions by Dr. Thomas Mether [2]
This is an excellent article for understanding why contemplative traditions have so much in common.
Real and unreal divine union by Archimandrite Sophrony [3]
An enlightened yoga adept who became the student of St. Silouan of Mt. Athos
Buddhism and Conversion to Orthodoxy - Q & A with Fr. John Matusiak [4]
Why Buddhists Might Be Interested In Orthodox Christianity [5] - from a Usenet posting by Reader John Simmons.
"Christian Zen, Christian Yoga, and Other Borrowed Practices [6]
From the book "Orthodoxy and the Religion of the Future. Written during the crazier '70s, much of this still applies to our time.
Why Christians Cannot Simply Dwell In A Natural State [7] - By St. Theophan the Recluse
Fr. Seraphim's writings are hard-hitting, but stand the test of Patristic discernment which is greatly lacking in our time. Do not be merely put off by Fr. Seraphim's statements, but get the essence of what is being said.
The vast gap between "Spiritualities" by Metropolitan Hierotheos Vlachos [9]
Epilogue from "The Psychological Basis of Mental Prayer in the Heart" by Fr Theophanes [10]
The whole book should be read, but this epilogue which summarizes key points of the book also sheds light on these topics.