Sickness is a defense against the truth.

No one can heal unless he understands what purpose sickness seems to serve. For then he understands as well its purpose has no meaning. Being causeless and without a meaningful intent of any kind, it cannot be at all. When this is seen, healing is automatic. It dispels this meaningless illusion by the same approach that carries all of them to truth, and merely leaves them there to disappear.
Sickness is not an accident. Like all defenses, it is an insane device for self-deception. And like all the rest, its purpose is to hide reality, attack it, change it, render it inept, distort it, twist it, or reduce it to a little pile of unassembled parts. The aim of all defenses is to keep the truth from being whole. The parts are seen as if each one were whole within itself.
Defenses are not unintentional, nor are they made without awareness. They are secret, magic wands you wave when truth appears to threaten what you would believe. They seem to be unconscious but because of the rapidity with which you choose to use them. In that second, even less, in which the choice is made, you recognize exactly what you would attempt to do, and then proceed to think that it is done.
Who but yourself evaluates a threat, decides escape is necessary, and sets up a series of defenses to reduce the threat that has been judged as real? All this cannot be done unconsciously. But afterwards, your plan requires that you must forget you made it, so it seems to be external to your own intent; a happening beyond your state of mind, an outcome with a real effect on you, instead of one effected by yourself.
It is this quick forgetting of the part you play in making your "reality" that makes defenses seem to be beyond your own control. But what you have forgot can be remembered, given willingness to reconsider the decision which is doubly shielded by oblivion. Your not remembering is but the sign that this decision still remains in force, as far as your desires are concerned. Mistake not this for fact. Defenses must make facts unrecognizable. They aim at doing this, and it is this they do.
Every defense takes fragments of the whole, assembles them without regard to all their true relationships, and thus constructs illusions of a whole that is not there. It is this process that imposes threat, and not whatever outcome may result. When parts are wrested from the whole and seen as separate and wholes within themselves, they become symbols standing for attack upon the whole; successful in effect, and never to be seen as whole again. And yet you have forgotten that they stand but for your own decision of what should be real, to take the place of what is real.
Sickness is a decision. It is not a thing that happens to you, quite unsought, which makes you weak and brings you suffering. It is a choice you make, a plan you lay, when for an instant truth arises in your own deluded mind, and all your world appears to totter and prepare to fall. Now are you sick, that truth may go away and threaten your establishments no more.
How do you think that sickness can succeed in shielding you from truth? Because it proves the body is not separate from you, and so you must be separate from the truth. You suffer pain because the body does, and in this pain are you made one with it. Thus is your "true" identity preserved, and the strange, haunting thought that you might be something beyond this little pile of dust silenced and stilled. For see, this dust can make you suffer, twist your limbs and stop your heart, commanding you to die and cease to be.
Thus is the body stronger than the truth, which asks you live, but cannot overcome your choice to die. And so the body is more powerful than everlasting life, Heaven more frail than hell, and God's design for the salvation of His Son opposed by a decision stronger than His Will. His Son is dust, the Father incomplete, and chaos sits in triumph on His throne.
Such is your planning for your own defense. And you believe that Heaven quails before such mad attacks as these, with God made blind by your illusions, truth turned into lies, and all the universe made slave to laws which your defenses would impose on it. Yet who believes illusions but the one who made them up? Who else can see them and react to them as if they were the truth?
God knows not of your plans to change His Will. The universe remains unheeding of the laws by which you thought to govern it. And Heaven has not bowed to hell, nor life to death. You can but choose to think you die, or suffer sickness or distort the truth in any way. What is created is apart from all of this. Defenses are plans to defeat what cannot be attacked. What is unalterable cannot change. And what is wholly sinless cannot sin.
Such is the simple truth. It does not make appeal to might nor triumph. It does not command obedience, nor seek to prove how pitiful and futile your attempts to plan defenses that would alter it. Truth merely wants to give you happiness, for such its purpose is. Perhaps it sighs a little when you throw away its gifts, and yet it knows, with perfect certainty, that what God wills for you must be received.
It is this fact that demonstrates that time is an illusion. For time lets you think what God has given you is not the truth right now, as it must be. The Thoughts of God are quite apart from time. For time is but another meaningless defense you made against the truth. Yet what He wills is here, and you remain as He created you.
Truth has a power far beyond defense, for no illusions can remain where truth has been allowed to enter. And it comes to any mind that would lay down its arms, and cease to play with folly. It is found at any time; today, if you will choose to practice giving welcome to the truth.
This is our aim today. And we will give a quarter of an hour twice to ask the truth to come to us and set us free. And truth will come, for it has never been apart from us. It merely waits for just this invitation which we give today. We introduce it with a healing prayer, to help us rise above defensiveness, and let truth be as it has always been:

Sickness is a defense against the truth.
I will accept the truth of what I am,
and let my mind be wholly healed today.

Healing will flash across your open mind, as peace and truth arise to take the place of war and vain imaginings. There will be no dark corners sickness can conceal, and keep defended from the light of truth. There will be no dim figures from your dreams, nor their obscure and meaningless pursuits with double purposes insanely sought, remaining in your mind. It will be healed of all the sickly wishes that it tried to authorize the body to obey.
Now is the body healed, because the source of sickness has been opened to relief. And you will recognize you practiced well by this: The body should not feel at all. If you have been successful, there will be no sense of feeling ill or feeling well, of pain or pleasure. No response at all is in the mind to what the body does. Its usefulness remains and nothing more.
Perhaps you do not realize that this removes the limits you had placed upon the body by the purposes you gave to it. As these are laid aside, the strength the body has will always be enough to serve all truly useful purposes. The body's health is fully guaranteed, because it is not limited by time, by weather or fatigue, by food and drink, or any laws you made it serve before. You need do nothing now to make it well, for sickness has become impossible.
Yet this protection needs to be preserved by careful watching. If you let your mind harbor attack thoughts, yield to judgment or make plans against uncertainties to come, you have again misplaced yourself, and made a bodily identity which will attack the body, for the mind is sick.
Give instant remedy, should this occur, by not allowing your defensiveness to hurt you longer. Do not be confused about what must be healed, but tell yourself:

I have forgotten what I really am, for I mistook
my body for myself. Sickness is a defense
against the truth. But I am not a body.
And my mind cannot attack. So I can not be sick.

- Jesus Christ in A Course in Miracles, Lesson 136