Yes, I think Lewis did pick up some such idea from Charles Williams. I seem to dimly recall there being a good deal about it in Williams' 1937 novel,
Descent Into Hell, which I skimmed over about twenty years ago.
A couple of minutes of Googling turned up this:
4.
The Doctrine of Substitution & the Way of Exchange—This is one of the ways that co-inherence can be actively practiced. Everyone participates in physical exchange (I am dependant on the farmers who produce my food; those who go to war die in the place of those who stay home and for whom peace is purchased, etc); we can choose to see these personal/social/political contacts as blessings and practice co-inherence in the strength of Christ’s resurrections. We can make compacts to bear one another’s burdens.
These principles can work among the living in any space and time, and also with the dead and the unborn.
The clearest explication of “The Doctrine of Substituted Love” comes in the chapter of that title in Descent into Hell, in which Stanhope carries Pauline’s fear for her, so she is no longer afraid to meet her doppleganger. Also, in chapter V of He Came Down from Heaven, Williams gives a non-fiction account of this principle. Williams claims that the mockery hurled at Christ on the cross, “He saved others, but he cannot save himself” was actually the rudimentary expression of a universal principle:
nobody can save himself, but we can voluntarily substitute ourselves for others and “carry their burdens” quite literally, even though those burdens may be spiritual, emotional, or medical. Martyrs and the Eucharist are examples of Christ in us and us in Him. Evil was consumed by good when Christ suffered on the Cross, and now our lives can be united to good in Christ’s earthly life.
In the Arthurian poems, this is also called the “doctrine of largesse.” Mordred enacts the opposite: he refused to depend on anyone and turned away from co-inherence to make sure everything worked for himself. The beginnings of substitution are expounded in “The Advent of Galahad.” In the “Founding of the Company” poem in The Region of the Summer Stars, Taliessin and his friends practice the way of exchange.'
http://iambicadmonit.blogspot.com/2007/ ... hemes.html I hope you find this more helpful than I have to date. Don't get me wrong : I am NOT saying there is nothing to it. On the contrary, I think there IS something to it, and that anyone who tries it is really playing with fire. I mean if you ask to carry the fear or sorrow or pain of another person (living or dead -- say, perhaps some long-ago martyr, or recent murder victim), you just might get what you're asking for, and it may be pretty tough if you're not really prepared for it.
There's a little more about it here. (I caution you that you may find out more than you wanted to know about Charles Williams here. He had been involved in what many would consider questionable things.)
' Simply stated, co-inherence is the concept that all human beings are spiritually interconnected and totally dependent on each other. "No man is an island" and so every thought and every action affects other people. In another terminology, humanity shares a "vast spiritual reservoir".
Williams took some trouble to emphasize that effective Exchange and Substitution did not require "intense states of natural love" or the "most advanced sacrificial victims of religion", but rather, could be implemented by "ourselves" and "the ordinary man". It operates in ordinary life, and does not require faith, but only "the first faint motions of faith". In the novel, Descent Into Hell Williams graphically dramatized the application and scope of exchange and substitution.
The practice of exchange and substitution implies that one can take, by a mutual agreement or compact, the mental, emotional or physical burdens of another. In Descent Into Hell Pauline allows her obsessive fear to be taken on by Peter Stanhope (an idealized Charles Williams figure). This exchange is presented as being comparable to allowing a friend to carry a parcel. The fear is a burden to Pauline because she has become overwhelmed by it: its assumption is a relatively small concern to someone who has his or her own inner state well regulated in that regard. As Williams pointed out elsewhere: "one may practice a virtue on behalf of another more easily than for ones self". The exchange does not have to be reciprocal with a specific person or for a similar kind of need. In the novel, an unburdened Pauline goes on to help the earthbound soul of a recent suicide, and, reaching further back in time, takes on the death of an ancestor, permitting him to die an exemplary death.
The actual mechanism of substitution and exchange is simple, though not always easy. The greatest obstacle, as any counsellor can testify, is often the unwillingness of the sufferer to let go of the root cause of their pain. It is important that the compact of exchange be mutual, particularly on the part of the sufferer. After the initial sympathetic exchange, the substitute is imagined as experiencing the symptoms instead. The substitute in turn privately visualizes the situation and accepts the pain and negativity. Because the substitute is more detached from the physical and emotional history of the suffer, the emotions are more easily balanced and the pain better endured.
As the practical working out of substitution and exchange is in the imagination and on the astral level, neither time nor distances are obstacles to its implementation. A change can be effected on the past from the present time using this technique. The main difficulty would lie in reaching a mutual consent across time. All the ethical aspects of the situation, especially with regard to the karmic responsibilities of others, would also require careful consideration. However, self-therapy, working on ones own time-line to modify past trauma from a balanced stance in the present, is a safe and profitable exercise.
Charles Williams warned of some dangers in the practice of exchange and substitution. Chief amongst these is "pretentiousness". Amazing feats and wonderworking are to be avoided: the Order of Co-Inherence is not to become a backdrop for ego-trips. Nor is anything to be promised that obviously can not be done. Williams emphasized the wisdom of beginning with the practice of small things: "To begin by practicing faith where it is easiest is better than to try and practice it where it is hardest". However, he also added: "There is little that could not be done". '
http://www.polarissite.net/page27.html David
"It is when we try to grapple with another man's intimate need that we perceive how incomprehensible, wavering, and misty are the beings that share with us the sight of the stars and the warmth of the sun." -- Joseph Conrad, Lord Jim(1899?)