In the Christian Science textbook, "Science and Health with Key to the Scriptures," Mrs. Eddy gives complete instructions for the utilization of the truths revealed in this Science in the overcoming of disease and discord of every nature. Such utilization is usually termed "treatment," and is a wholly mental and spiritual process or activity. The following statement of the method of treatment is to be found on page 418 of this textbook: "Stick to the truth of being in contradistinction to the error that life, substance, or intelligence can be in matter. Plead with an honest conviction of truth and a clear perception of the unchanging, unerring, and certain effect of divine Science. Then, if your fidelity is half equal to the truth of your plea, you will heal the sick."
To succeed in attaining measurably to that which is called for in the foregoing paragraph places upon the student the necessity for much consecrated study and self-examination. In order to "stick to the truth of being" it first is necessary to know the truth, which knowing can be gained only by reverent and receptive study of the Bible and the works of our Leader, the one who has revealed the spiritual meaning of the Scriptures. To "stick to the truth of being in contradistinction to the error" calls not only for a knowledge of the truth, but also for a clear perception and firm assurance of the fact that whatever is evil, whatever is not good, harmonious, spiritual, and perfect, is error. If we are to "stick to the truth of being" in contradistinction to error, we cannot hold to both the truth and error. We must reject the error—"the error that life, substance, or intelligence can be in matter."
As used in law terminology, to plead a case means to present it fully to the court. The plea of the attorney is the complete statement of the case—its factual structure, the law involved, authoritative references pertaining to similar cases, and the argument, based on the facts and the law. Thereby the attorney arrives at the conclusion and affirmation of the rightness and equity of the case as presented. It is in this sense that we are indeed to "plead" concerning the matter under consideration, "with an honest conviction of truth" and with the assurance, derived from the student's own experience and understanding, that the law of God is the law of infinite good, perfection, and peace, and that the affirmations which are included in a Christian Science treatment are as definitely true about the particular issue involved as they are about the entirety of God's creation. Such assurance and certainty afford the student the needed "clear perception of the unchanging, unerring, and certain effect of divine Science," that clear perception which leads to the realization of the absolute perfection of every unit of God's creation, from the infinitesimal to the infinite.