During his early career, John Sack worked as a technical writer in the computer, astrophysical and environmental fields. In addition to countless user manuals, he published two computer textbooks, both through Science Research Associates. These were: Entering BASIC, a programming tutorial, and Fundamentals of IBM Computing Systems, an introductory guide to computers predating the Internet.

In 1985, Paulist Press published The Wolf in Winter, a young-adult novel about the teen years of St. Francis of Assisi. The research John did for this book inspired his adult novel, The Franciscan Conspiracy.

Hohm Press of Prescott, Arizona published Yearning for the Father: the Lord’s Prayer and the Mystic Journey in 2006. John draws on history, literature, poetry and his first-hand appreciation of other religious traditions to present an extended meditation on these much-loved words of Jesus. He also examines the Aramaic roots of the Lord’s Prayer to suggest interpretations beyond the traditional Western understanding.

Leaving My Broken House, a prose and haiku travel sketch in the tradition of Matsuo Basho, is planned for 2007 publication by Caveat Press of Ashland, Oregon.