In October 1862, Eddy became a patient of Phineas Quimby, a mental healer from Maine.
From 1862 to 1865, Quimby and Eddy engaged in lengthy discussions about healing methods practiced by Quimby and others.
The extent to which he influenced her is much debated.
Originally, Eddy gave Quimby much credit for his hypnotic treatments of her nervous and physical conditions and initially thought his brand of mesmerism entirely benign.

Quimby wrote in 1864, "The wise man, in like measure ... knows that the light of the body or natural man is but the reflection of the scientific man.
Our misery lies in this darkness.
This is the prison that holds the natural man, till the light of Wisdom bursts his bonds, and lets the captive free.
Here is where Christ went to preach to the prisoners bound by error before the reformation of science."
In a letter to the Portland Evening Courier in November 1862, Eddy wrote: "With this physical and mental depression I first visited P. P. Quimby, and in less than one week from that time I ascended by a stairway of one hundred and eighty-two-steps to the dome of the City Hall, and am improving ad infinitum.
To the most subtle reasoning, such a proof, coupled to as it is with numberless similar ones, demonstrates his power to heal."}}

She wrote in a letter in 1864: "I am up and about today, i.e., by the help of the Lord."
Eddy denied mesmerism in another letter to the Portland Evening Courier, claiming that Christ was the cure:
P. P. Quimby stands upon the plane of wisdom with his truth.
Christ healed the sick, but not by jugglery or with drugs.
As the former speaks as never man before spake, and heals as never man healed since.
Christ, is he not identified with truth, and is not this the Christ which is in him?
We know that in wisdom is life, `and the life was the light of man.'
P. P. Quimby rolls away the stone from the sepulchre of error, and health is the resurrection.
But we also know that light shineth in darkness, and the darkness comprehended it not.

Quimby had his own notions concerning the nature of these unseen forces which Eddy accepted early on, but she later drew decidedly different opinions on the nature of thought on the body and rejected any form of hypnotism.
It is evident that Eddy and Quimby worked together, appreciated one another, and learned from one another.
Quimby reportedly later said that he learned more from Eddy than she did from him.
Eddy clearly respected him and, at one point, referred to him as an "advanced thinker" with a "high and noble character".
She later disavowed the hypnotic aspect of Quimby's methods.
In Science and Health with Key to the Scriptures, she calls hypnotism mere deception practiced by those who aim to control the patient: "The Christian Scientist demonstrates that divine Mind heals, while the hypnotist dispossesses the patient of his individuality in order to control him."
In October 1862, Eddy became a patient of Phineas Quimby, a mental healer from Maine. From 1862 to 1865, Quimby and Eddy engaged in lengthy discussions about healing methods practiced by Quimby and others. The extent to which he influenced her is much debated. Originally, Eddy gave Quimby much credit for his hypnotic treatments of her nervous and physical conditions and initially thought his brand of mesmerism entirely benign.
Quimby wrote in 1864, "The wise man, in like measure ... knows that the light of the body or natural man is but the reflection of the scientific man. Our misery lies in this darkness. This is the prison that holds the natural man, till the light of Wisdom bursts his bonds, and lets the captive free. Here is where Christ went to preach to the prisoners bound by error before the reformation of science." In a letter to the Portland Evening Courier in November 1862, Eddy wrote: "With this physical and mental depression I first visited P. P. Quimby, and in less than one week from that time I ascended by a stairway of one hundred and eighty-two-steps to the dome of the City Hall, and am improving ad infinitum. To the most subtle reasoning, such a proof, coupled to as it is with numberless similar ones, demonstrates his power to heal."}}
She wrote in a letter in 1864: "I am up and about today, i.e., by the help of the Lord." Eddy denied mesmerism in another letter to the Portland Evening Courier, claiming that Christ was the cure:
P. P. Quimby stands upon the plane of wisdom with his truth. Christ healed the sick, but not by jugglery or with drugs. As the former speaks as never man before spake, and heals as never man healed since. Christ, is he not identified with truth, and is not this the Christ which is in him? We know that in wisdom is life, `and the life was the light of man.' P. P. Quimby rolls away the stone from the sepulchre of error, and health is the resurrection. But we also know that light shineth in darkness, and the darkness comprehended it not.
Quimby had his own notions concerning the nature of these unseen forces which Eddy accepted early on, but she later drew decidedly different opinions on the nature of thought on the body and rejected any form of hypnotism. It is evident that Eddy and Quimby worked together, appreciated one another, and learned from one another. Quimby reportedly later said that he learned more from Eddy than she did from him. Eddy clearly respected him and, at one point, referred to him as an "advanced thinker" with a "high and noble character". She later disavowed the hypnotic aspect of Quimby's methods. In Science and Health with Key to the Scriptures, she calls hypnotism mere deception practiced by those who aim to control the patient: "The Christian Scientist demonstrates that divine Mind heals, while the hypnotist dispossesses the patient of his individuality in order to control him."
Mary Baker Eddy