From “A Course in Miracles”
“To heal is to make happy. I have told you to think how many opportunities you have had to gladden yourself, and how many you have refused. This is the same as telling you that you have refused to heal yourself. The light that belongs to you is the light of joy. Radiance is not associated with sorrow. Joy calls forth an integrated willingness to share it, and promotes the mind’s natural impulse to respond as one. Those who attempt to heal without being wholly joyous themselves call forth different kinds of responses at the same time, and thus deprive others of the joy of responding whole-heartedly.
To be whole-hearted you must be happy. If fear and love cannot coexist, and if it is impossible to be wholly fearful and remain alive, the only possible whole state is that of love. There is no difference between love and joy. Therefore, the only possible whole state is the wholly joyous. To heal or to make joyous is therefore the same as to integrate and to make one. That is why it makes no difference to what part or by what part of the Sonship the healing is offered. Every part benefits, and benefits equally.
You are being blessed by every beneficent thought of any of your brothers anywhere. You should want to bless them in return, out of gratitude. You need not know them individually, or they you. The light is so strong that it radiates throughout the Sonship and returns thanks to the Father for radiating His joy upon it. Only God’s holy children are worthy channels of His beautiful joy, because only they are beautiful enough to hold it by sharing it. It is impossible for a child of God to love his neighbor except as himself. That is why the healer’s prayer is:
‘Let me know this brother as I know myself.’ “
Chapter 5, “Healing and Wholeness”. A Course in Miracles. Volume 1