"Mortal mind" is the name Christian Science gives to the supposititious counterfeit of the one and only Mind, God. Mrs. Eddy explains: "Mortal mind is a solecism in language, and involves an improper use of the word mind. As Mind is immortal, the phrase mortal mind implies something untrue and therefore unreal; and as the phrase is used in teaching Christian Science, it is meant to designate that which has no real existence." Science and Health, p. 114;
So mortal mind is a name. It is not a mind. It is not an intelligence. It is a myth, an illusory, false sense, deriving its appearance of power from the universal belief in it and in its deceptive, material presentations.
An understanding of mortal mind's nothingness is vital in the healing practice of Christian Science. Mortal mind's power to sustain the discordant material falsities it supposedly conceives and believes in is proportionate to the individual's belief in this mind as real. We should guard against endowing mortal mind with what it can never actually have—the attributes of Mind.