Did Mary Baker Eddy say it? “Sea captains on shore …”

Mary Baker Eddy to Laura E. Sargent, February 22, 1895, L05975.
“Sea captains on shore are of no use.” Our research staff sometimes answers questions about these words attributed to Mary Baker Eddy. Did she ever make this statement, or something similar? If so, in what context?
These are, in fact, Eddy’s words.1 They can be found in a letter that she wrote to her student Laura E. Sargent on February 22, 1895. Sargent had apparently asked how students of Christian Science can grow as healers. Here’s how Eddy responded:
What you and all students need most to advance their growth is practice healing the sick[.] Sea captains on shore are of no use[.] All your theory will prove worse than useless to you unless you practice it in proof of it for yourself[.] Taking patients is the only way to do this.2
That was a busy time for Eddy. A month earlier, the Original Edifice of The Mother Church had been completed and dedication services held. Also in January, readings from the Bible and Science and Health with Key to the Scriptures, which she had first published in 1875, had replaced personal preaching. (Eddy had ordained the two books as The Mother Church’s pastor in December 1894.) Her correspondence from this period was mostly focused on answering questions and figuring out details related to the new church edifice and the new pastor. But this letter makes it clear that a focus on healing would always be the priority!