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About Us

Born in 1931 out of the traumatic WWI experiences of Dr. Thurman Fleet, who could not find solutions to his challenges from traditional medicine and theology, what is known today as Concept-Therapy has evolved into a non-profit educational organization. Grounded in philosophical principles that trace back centuries, Concept-Therapy is a unifying correlation of the fundamental disciplines (Science, Metaphysics, Theology, Psychology, Sociology, and Philosophy). It has been taught continuously at its San Antonio Campus for nearly seven decades, where it has proven itself a viable, workable understanding of living a whole life. Over the course of this remarkable tenure, Concept-Therapy has provided an anchor of support for 1000’s of people aspiring to a life of health, happiness, peace, and success and is now taught in locations across the United States and Canada.


With only a meager formal education and against tremendous odds, Fleet was an ordinary man who aspired to the extraordinary.  As an infantryman, he earned a battlefield commission from the U. S. Army in World War I and became one of the nation’s most highly decorated soldiers of that conflict.  He emerged from the war an “old man” of 23, suffering physically and mentally.  Effects of mustard gas and shrapnel in his skull, and haunting, horrific memories plagued the young hero.  Army doctors offered him little relief and no hope.  With a family to provide for, he began a fascinating odyssey to rebuild his health and life.  His journey led him into the realms of psychology, philosophy, theology, health and healing.  Thurman Fleet regained his health and attended the Texas Chiropractic College, establishing a highly successful Chiropractic Clinic in San Antonio, Texas. Dr. Fleet devoted his life to searching for, organizing and teaching the truth about the human condition in all its complexity.  His legacy is Concept-Therapy.

What We Teach Dr. Fleet

The History and Life of Dr. Thurman Fleet

San Antonio Educational Center

In 1944, Dr. Thurman Fleet began teaching his philosophy to members of various healing professions, primarily chiropractors, and in 1949 he founded the Concept-Therapy Institute, a non-profit educational organization in the state of Texas open to all students interested in the study of this philosophy. He purchased the Aum-Sat-Tat Ranch, located in the Texas Hill Country, as a unique destination for study, collaboration, and contemplation.

CTI plays host not only to instructors delivering Concept-Therapy seminars, area meetings, conventions, and training courses but also to a number of national organizations whose members retreat here in the heart of the Hill Country each year. Visitors and guests are welcome at “The Ranch,” and inquiries are accepted at the Institute Monday through Friday, 9:00 a.m. until 4:00 p.m.

Our Vision

At Concept-Therapy we are building a world where all people are healthy and whole in mind, body and spirit.

Our Mission

Concept-Therapy offers a comprehensive learning opportunity for people aspiring to a life of health, happiness, success and peace.

Board Members

Raymond Gravelle


Leigh Zachary


Raymond Gravelle started taking Concept-Therapy classes in southern California with the Mattox/Burgess Team in 1975. A few years later he took the Cosmic Principles class thus completing all the coursework including becoming a Certified Teacher. Raymond and his wife Debra live in Soap Lake, Washington where he was Mayor for eight years. His diverse background ranges from being a Military Police Dog Handler in the Army to working for marketing and advertising companies, to positions on several non-profit boards including serving as a Grant County Hospital District Commissioner and currently serving as President of the Grant County Association of REALTORS®.  “Being part of Concept-Therapy’s leadership team is a lifelong dream for which I am deeply honored.” 

Leigh is a second-generation Beamer taking his first Concept-Therapy class in 1978 from Dr. Herb Dill and Emily (Dill) Mattox. He has taken all of the Concept-Therapy and Conceptology classes and has reviewed them all many times. Regularly attending Beam Club and Pathseeker Club, he has received the Concept-Therapy Commendation Award and is also currently the IOTBC Bombardier. Carrying on the family tradition are his two children who have also begun taking Concept-Therapy classes. He received his BS in Economics (minor in Statistics) from Texas A&M University and is the owner of a financial services company in The Woodlands, TX. He has coached numerous baseball and football teams, been Captain of the Events & Functions Committee for the Houston Livestock Show and Rodeo and his favorite things to do are snow ski, be outside and act like a pro at taking power naps.

Mark Oholendt



Bonnie Jo Chastain


Mark Oholendt is a retired Alliance Manager and Account Executive with the NCR Corporation. Mark graduated summa cum laude from the University of Texas at San Antonio with a BBA in Management.   Mark and his wife Katherine (a retired elementary teacher) first took Concept Therapy in the 1970s, have been happily married for 41 years, and are blessed with three children. They are Pathseekers and have taken all the work. Both are involved as volunteers with the University Health system in San Antonio, engaged in providing pet therapy with their rough collie dogs Prince and Laddie. Mark has taught in over 40 classes and has received the numbered W and Zero awards from CTI.

First introduced to Concept Therapy in 1975 by The Lynn Teaching Team, Bonnie has had all the classes through Cosmic Principles. Born and raised in Davenport, Iowa she now lives in Athens, Georgia where she serves on the Development Authority of Athens/Clarke County. She is also a Master Gardener, giving lectures to civic organizations, garden clubs and governmental departments. She looks forward to being a part of strengthening the Concept Therapy organization so it is available to larger groups of people who are searching for answers.

Robin Brunk-Dawson


Dr. Cassie Mattox, Ed.D.

Board Member

IOTBC Chief Pilot Robin Brunk-Dawson has been a Beamer since 1982. She has taken every course CTI offers except Chiropractic Principles, primarily from the Dawson-Harrison, Mattox, Lynn, Craig, and Vic & Gwen Loofboro teaching teams. She has served in all positions in Beam and Pathseeker clubs and actively teaches with her chiropractor husband, Dr. Bill Dawson, at their Double Triangle Ranch in California’s high desert region. She encourages Beamers to contact her.

Dr. Cassie Mattox, Ed.D. The eldest daughter of Charles and Emily Mattox, long-time teachers/proponents/supporters of the philosophy, Cassie brings not only her lived experience of Concept-Therapy, but her seasoned experience as a professional educator. As an educational organization whose mission is to “offer a comprehensive learning opportunity for people aspiring to a life of health, happiness, success, and peace,” Cassie offers her cumulative academic, social, and professional experiences, as well as her desire to give back in service to Life. She lives in Georgia with her daughter their dog and two cats. In her free time, Cassie enjoys volunteering at her daughter’s school, exploring parts of GA, and visiting family and friends back in TX.

Tred Rissacher DC


Dr. Tred Rissacher was introduced to Concept-Therapy in 1972. He has completed all the work and is a certified teacher of Concept Therapy, and his entire family began Concept Therapy in the early 70s and they have completed the entire work through Cosmic Principles. He graduated from Cleveland Chiropractic College in 1988 and has been in the professional chiropractic practice for 33 years. “My relationship with chiropractic and Concept Therapy is the most important aspect of my life.”

Concept-Therapy Institute is a state-chartered, non-profit, federally tax-exempt educational organization as defined in Section 501 ( c ) ( 3 ) of the Internal Revenue Code.

2019 Form 990 for Concept Therapy Institute Inc.

2020 Form 990 for Concept Therapy Institute Inc.

2021 Form 990 for Concept Therapy Institute Inc.