William Garner Sutherland came to study the osteopathy of Dr. Andrew Taylor Still in 1898 and found within that study a lifetime's work. This volume of his collected writings, Contributions of Thought, represents that work, which Adah Sutherland described in the preface to the first edition as depicting the progress of an "original thinker."

She went on to say: “With a steadfast sense of personal responsibility, Dr. Sutherland accepted Dr. Andrew Taylor Still’s admonition that D.O. stands not only for Doctor of Osteopathy but for “dig on” as well. His writings convey that he did so, consistently I like to believe that the attentive reader will see revealed in these writings how Dr. Sutherland’s self-imposed “digging” heightened his comprehension of osteopathic philosophy and its application in practice. It was through this constructive discipline that he was guided, to his own amazement, into the channel of cranial research. This perseverance culminated in his contribution of the cranial concept to the osteopathic profession – ‘osteopathy in the cranial field’.'”

This is a compilation of papers by William Sutherland that are organized in chronological order, and in these you see the development of his research into osteopathy in the cranial field. Things start to get very interesting around 1948 when he starts mentioning “Liquid Light” and other esoteric aspects of osteopathy. This is an essential text in the osteopathic literature.