A key is a tool, not an objet d'art or a talisman to be ritualistically thumbed in purse or pocket. If it isn't used to unlock or activate something a key serves no purpose. We often think of the textbook of Christian Science simply as Science and Health, but we know it is also with Key to the Scriptures. That key is not a metaphysical abstraction.
Mrs. Eddy obviously intended the Key to the Scriptures to be used to unlock the spiritual meaning, the inspired Word, of the Bible. The first tenet of Christian Science states: "As adherents of Truth, we take the inspired Word of the Bible as our sufficient guide to eternal Life." (S&H 497: 3-4) Wouldn't we be wise to use this priceless key daily to unseal and open that wilderness in which we abide? Keys are to something, not ends in themselves.
Note: Readers of this blog might be interested in an excellent article which dovetails satisfyingly with several recent and earlier entries. Had this article been reread earlier, some of these lucubrations might not have seemed necessary. It is "Defending the Purity of Church", by Maurice W. Hastie, from the C. S. Journal, Volume 83, April 1965. It was reprinted, where it was recently found, in one of those tasty pocket pamphlets of yesteryear titled "Handling Animal Magnetism". The entire pamphlet is worth reading if one is fortunate enough to own or find a copy.