Mary Baker Eddy first considered using marginal headings in Science and Health with Key to the Scriptures in 1889, and the 50th edition of the book (published in 1891) was the first to contain them.
From the beginning, these headings were products of collaboration between Eddy and those who assisted her. While working with various assistants, she always maintained complete control over any changes made to Science and Health, including the marginal headings.
For more information, we suggest this article from The Christian Science Journal:
“Science and Health: textbook for self-improvement” (September 1993)
http://journal.christianscience.com/shared/view/1z5ekwawqxc?s=t
