"One Law of the Action of the Soul on the Body, & vice versa, seems to be, That upon such and such Motions produced in the Musical Instrument of the Body, such and such Sensations should arise in the Mind; and on such and such Actions of the Soul, such and such Motions in the Body should ensue; much like a Signal agreed to between two Generals, the one within, the other without a Citadel, which should signify to one another, what they have before agreed to, and established between them; or, like the Key of a Cypher, which readily explains the otherwise unintelligible Writing."
An Essay of Health and Long Life
Cheyne, George. <u>An Essay of Health and Long Life</u> (London: George Strahan, 1724). &lt;<a href="http://books.google.com/books?id=5wIAAAAAQAAJ">Link to Google Books</a>&gt;