[This] diagram attempts to illustrate the development of Christian Spirituality through the centuries. The first four centuries form part of the essential theological background for a study of the Schools.
1. The fourteen most fundamental and significant Schools are in bold caps, e.g., BENEDICTINE. They are followed by the most significant writers of that School.
2. Proper names in caps, e.g. BASIL, are writers whose basic theology is significant to ascetical theology, and which has given rise to a particular School, e.g., Augustine—Austin Canons Regular—Victorine School; Aquinas—Dominican School.
3. Lower case indicates important schools or movements but of lesser significance to the student of Spiritual Direction, e.g., Quakers.
4. Bracketed lower case indicate important historical developments, illustrative of original spiritual thrusts, but which have left little or no ascetical theology in writing, e.g., (Gilbert of Sempringham).
The overall purpose here is to try to produce a logical scheme of study over five, ten, fifteen years; to provide a basic background plan in outline, which may be filled in as students advance. Absolutely no judgmental inference is implied as to the intrinsic value of a School or writer. There are purposeful omissions for the sake of clarity. A plan containing hundreds more entries, spread over a couple of square yards, could be produced. I do not think that it would help!
[Diagram and text from Appendix I of Spiritual Direction by Martin Thornton]