The thoughts we entertain are far-reaching in their effects on our physical health and well-being—therefore we should control them. Good thoughts appear as healthy, harmonious bodies and conditions, while corrupt thoughts produce discord and disease.
Mortal thoughts don't just lie dormant in secret compartments of the mentality, doing no good and no evil, even though we may think we are concealing them. They are always liable to be objectified to the physical senses as matter and material conditions. It is highly important to our human welfare, therefore, to take good care of our mentalities and accept into consciousness only that which will be productive of health and harmony, and refuse admittance to evil, matter-oriented thoughts, which will inevitably result in discord.
Mrs. Eddy makes this clear in her book Retrospection and Introspection where she writes, "The mortal body being but the objective state of the mortal mind, this mind must be renovated to improve the body." Ret., p. 34; And in Science and Health she warns, "We should become more familiar with good than with evil, and guard against false beliefs as watchfully as we bar our doors against the approach of thieves and murderers." And she continues farther on, "You must control evil thoughts in the first instance, or they will control you in the second." Science and Health, p. 234;
