Masao Abe was a Zen Buddhist scholar from Kyoto, Japan.

Abdol Reza Arasteh was born in Shiraz, Iran, in 1927. He had studied both Eastern and Western psychology and seemed to bridge Merton's earlier interest in psychology with his later interest in Sufism, Zen and other eastern traditions. He lived a number of years in the United States and became a citizen in 1976. (Source: «The Hidden Ground of Love», p. 40-41.)

Living in Karachi, Pakistan, Abdul Aziz can be attributed with sparking Merton's first interest in Sufism, an interest later shared with his novices at Gethsemani. Beginning their correspondence in late 1960, Merton and Aziz would exchange books and ideas. Aziz was introduced to Merton's work through Louis Massignon, a mutual friend. An important insight from these letters is Merton's response to Aziz's request for a description of his prayer life.