A sunday school teacher had found the marginal headings in the Christian Science textbook, "Science and Health with Key to the Scriptures" by Mary Baker Eddy, very helpful in studying the various sections of the weekly Lesson-Sermon. One week when the subject for the Lesson was "Truth," a reference on page 295 of the textbook stood out particularly. It read, "The mortal mind through which Truth appears most vividly is that one which has lost much materiality— much error—in order to become a better transparency for Truth." The marginal heading for the paragraph is, "Goodness transparent." Observing for the first time the two words in combination produced such a startling effect on the teacher's thought that she asked her class the following Sunday to consider the heading and to give the meaning of transparent.
After one girl had pointed out that the glass in the door was transparent because she could see through it, the teacher gave some of the dictionary definitions, as follows: "Having the property of transmitting rays of light. Readily understood; clear."
To further elucidate the subject, the class was asked for a word representing the exact opposite of transparent. The word "opaque" was agreed upon and the following definition cited: "Not reflecting or giving out light. Impervious to the rays of light; not transparent."
