Here, you can read the THE ONLY PARAGRAPH in the entire Course where a "shift in perception" is mentioned in connection with "miracles". There are NO other references to this and there is not even a single reference to any kind of "shifting" OR changing of perception in relation to "miracles" mentioned within the same context or section of text, anywhere.
I am going to explain what it really means and what a MIRACLE is, below.
"The miracle minimizes the need for time. In the longitudinal or horizontal plane the recognition of the equality of the members of the Sonship appears to involve almost endless time. However, the miracle entails a sudden SHIFT from horizontal to vertical perception. This introduces an interval from which the giver and receiver both emerge farther along in time than they would otherwise have been. The miracle thus has the unique property of abolishing time to the extent that it renders the interval of time it spans unnecessary."
So, for a start, the "shift" referred to is in the context of the collapsing of time, and not so much talking about the so-called "shifts in perception" that you undergo when you are correcting/purifying the mind. But it does mention perception.
The KEY sentence is this: "The miracle entails a sudden SHIFT from horizontal to vertical perception."
Now, we need to understand what the Course means by a "horizontal perception" and a "vertical perception" and how they are different and what exactly is "entailed" by "shifting" from one to the other.
"Horizontal perception" is ego perception. It means that you believe in and are perceiving causes on this level, which are producing effects on this SAME level. Therefore it seems that cause and effect are operating sideways. So for example, if it SEEMS as if a person throws a ball at another person and it hits them on the head, person A is the cause and person B is affected. This illusion sets up a scenario of victimhood, if the people are thinking with the ego.
On the surface it appears there was an independent, separate cause on this level, which produced independent, separate effects in some other part of this level. This way of perceiving relies on separation and fragmentation of the level, ie multiple separate individual causes and effects. And also in horizontal perception, it is believed that a cause "escapes" from the effects it produces, so is not at the effect of itself and can get away with murder.
Horizontal perception is a murderous thought system of attack and the attempt to deny effects ie to deny oneness, to have separate rules for separate individuals, to perceive inequality and to seem capable of attacking without being attacked. This is all "standard" within horizontal perception. It's ego perception.
"Vertical perception" is very different to this. Instead of looking sideways for causality on this level, or thinking that this level causes effects in a higher level, perception instead places you IN GOD, ie in truth/heaven, looking DOWNWARDS upon the lower level (this world).
From that higher perspective, it is seen that the ENTIRE world is one dream, it is all coming FROM the higher level, the higher level is the cause of it, all of the things happening in the world are EFFECTS ONLY, there ARE no causes in the world on the horizontal level, and therefore there also are no victims, no possibility of one part of the world attacking another, and no separated opposing wills working against each other. It is the perspective of God, or the perspective of the dreamer of the dream.
In vertical perception, you literally RECOGNIZE that everything in this world/lower level is expressing FROM the higher level, thus mind is the cause of everything that's showing up, and there are no other causes of anything. That means there is no horizontal cause of sickness or death. There is nothing that is happening or showing up in the world which "explains" or "justifies" or "causes" anything else on the same level. So someone does not die from a car crash, someone is not sick because of bad food, someone is not suffering with PTSD from a war, someone is not lacking money because someone stole it, etc. No horizontal causes whatsoever.
Instead, vertical perception sees that there can be no victimhood, there are NO causes on the level of form, the entire universe is an effect, mind is the cause, mind has all the power, mind has projected this entire world and it can CHANGE ANYTHING if it so chooses. When it changes something, it basically goes behind the back of any fictional "horizontal laws", which includes all of the laws of physics, biology, chemistry, etc, and pulls the plug on them.
That means, while it is physically impossible for a physical object to suddenly disappear from one location and show up in another, based on the horizontal laws of causality, "vertically" this is absolutely effortless. The vertical mind can choose, from above, to simply undo the projection of the object and to project another object somewhere else. To the observer on the physical level it will seem like A MIRACLE! A demonstration of what appears to be horizontally impossible. A law-breaking, physics-defying demonstration that the horizontal laws ARE NOT TRUE, and that the laws of God ARE TRUE.
This is also the true meaning of "there is no order of difficulty in miracles". They are all the same because all that happens is a vertically-perceiving person who does not buy into any of the horizontal illusions/laws whatsoever, decides to rearrange the illusion in a way which completely defies all of the laws and which horizontal-believing people find to be impossible. If at first a person appeared dead, and if the horizontal laws say that once death occurs there is no going back, and the vertically perceiving person decides to remove the dead body and put life back into it and manifest a living body in its place, THAT IS A MIRACLE.
A miracle is an expression, rooted in love, aligned with the Atonement (vertical truth), which CAUSES FROM ABOVE, and produces effects BELOW (e.g. in the physical level). And since all such acts are basically the SAME ACT of causality from above to below, it does not matter whatsoever what the below rules say should be possible, or what seems more difficult or easy, or the magnitude of the effects, or how long lasting they have been, or how many times a person was caused, or how long sickness has been present, or how long someone is dead for. None of it matters vertically because love expresses maximally from above, will full power and effect below, and everything is essentially the SAME ACTION. One problem, one solution.
Now, we need to therefore recognize that when someone is in the ego mindset, if they are trying to apply the course and are trying to shift perception or have a healing or receive a correction, the only "actual" healing possible is to move in the direction of the vertical.
However, if we are being honest here, a person who is just starting out with this and who has a "little" willingness and accepts a small correction, can barely be called a miracle worker. They may "shift" from 99% horizontal perception, to 98.5% horizontal perception. A very slight shift away from horizontal toward vertical truth. And that person WILL NOT be able to move mountains. They will not be able to reverse death nor will they be able to heal the blind etc.
Each little shift in perception gradually, slowly, over a long period of time, moves the person from the horizontal upward toward God. And it takes a LOT of purification work to do this. A huge amount of investment in horizontal ego perception must be let go in order to move upwards. And there is NOT a "sudden shift" here. You do not suddenly go from heavy ego investment to "no ego" in the blink of an eye (at least almost never). We're not talking about going from horizontal to "slightly more vertical" perception. A miracle entails a shift ALL THE WAY to vertical perception.
Notice also it says "entails", which doesn't necessarily mean "is". It's not saying a miracle IS a shift to vertical perception. It ENTAILS getting into vertical perception first. You need to get your mind up there into the perspective of God, first, before you will be able to perform a miracle. And for most people that is going to take YEARS of dedicated undoing and correction, which the course calls PURIFICATION. It's not even the same thing as forgiveness.
Now, there are parts in the Course where Jesus makes a distinction between being "miracle ready" and the actual "action" of performing a miracle. Miracle readiness means being in vertical perception at all times. Actually PERFORMING a miracle, which expresses FROM love, in a vertical direction, producing changes in EFFECTS on the level of this world (almost always observable), is a separate part of being miraculous. You don't just sit there "being miraculous". It is not a spectator sport. Members of Jesus's party are ACTIVE WORKERS. There is an activity involved. A USE of the POWER of causality. An EXPRESSION of it to where love was LACKING, providing what was lacking, so that LIFE is restored and death is reversed. (Miracles fulfill a lack).
So the "shifting of perception" from fear to love, or from ego to truth, or from darkness to light, or from death to life, is not ITSELF a miracle. Miracles flow DOWNWARD FROM HEAVEN. "Miracles fall like drop of healing rain from heaven on a dry a dusty world where starved and thirsty creatures come to die." They come DOWN from ABOVE, not up from below, and they are not your movement upwards. Nor do they flow sideways. A sideways shift in perception is not a miracle. A slight shift towards vertical perception is not a miracle. A person is not performing miracles by MOVING UPWARD, they perform miracles by expressing FROM a high place, downward, which then LIFTS upward. The shifting of perception towards God is an EFFECT of a miracle, not a cause.
It is in fact the EGO which likes to believe that IT is a miracle worker. It does this through level confusion, which is the belief that a lower level causes a higher level. In this belief, the ego says, well, if I shift my perception toward truth, then I am being causal and am triggering a miracle. Or as if, the shifting itself is a cause, and it produces vertical effects. This is A LIE. This is classic ego thinking. God is cause, not the ego. Cause comes DOWN from above, not up from below.
Miracles ENTAIL a shift into a vertical perceiving mode, FIRST, in order to SEE with God's eyes, to recognize suffering for the illusion it is so that you do not make it real, and then LOVE EXPRESSES. The expression of love is downwards from God. Causality flows vertically, from God, to us. Getting your perception INTO a state of perceiving vertically IS NOT a miracle, it is PREPARATION for a miracle.
Recognize that miracles are rooted in forgiveness and forgiveness is a HIGH STATE of mind, in which there is nothing LEFT to forgive. It is the atonement. Forgiveness, atonement, salvation, are all the same thing. They are end goals after a great deal of purification work and much correction of perception. Correction of perception is not a miracle, but miracles DO have a corrective function.
They are extensions of, expressions of, the atonement principle, once it has ALREADY been accepted. Atonement has to be RECEIVED, BEFORE miracles can be GIVEN. You can only give the miracles you have received, and miracles are something you SHARE and GIVE, not something that you "only receive". You cannot express a miracle UNTIL you accept atonement, and you cannot accept atonement UNTIL you have "shifted perception". So the shifts in perception have to happen FIRST, over a long period of time, gradually, to get your mind to where you are WILLING to ACCEPT the atonement, and THEN you will be willing to RECEIVE, and THEN you will be ABLE to extend and perform a miracle. You cannot give miracles you have not received and that means you cannot express atonement if you have not accepted it yet!
You can't sit there and think, well, I just shifted "my perception" and so "I" have now received a "miracle" in isolation, which only I have benefited from, and it has no causal effects on anyone else. Giving and receiving are one, and once you accept atonement you GO OUT and you extend the atonement to others and HELP OTHERS. Miracles are services to others FROM a state of love, not little stepping stones in your own awakening.
Miracles can rearrange time because they operate from above and outside of time and therefore can DEFY linear/horizontal causality/time. Does shifting your perception rearrange time? Does it have effects which are POTENTIALLY SPECTACLES, which you then have to be careful not to use AS spectacles (ie for that sake alone)? Could you describe your own correction of your own perception, something that could have the "risk" of being considered SPECTACULAR in the eyes of other people, with effects so extraordinary (like Jesus appearing out of thin air after having "died")? Not likely.
Jesus walking on water to prove that gravity means nothing and He is not under the laws of the horizontal, THAT is a miracle. Jesus completely defying all laws by MULTIPLYING a few loaves of bread and fishes enough to feed 5000 people, that is a MIRACLE. Jesus raising someone from "certain death" and reversing death and restoring him to a living state, that is IMPOSSIBLE on the horizontal level of laws (death is irreversible), but He proved that it is NOT irreversible, because he has his hand on the "controls" of this entire world "there is nothing my holiness cannot do."
If it is not supernatural, it is NOT a miracle. It there is not some kind of causality coming from above and expressing below and BREAKING the ego's laws, it is NOT a demonstration of God's truth and is not a miracle. If it is merely someone having a personal healing in the privacy of their home and perceiving slightly more truthfully afterwards, that is NOT a miracle. It is merely a stepping stone TOWARDS being able to let miracles flow. If all expressions of love (FULL love) are a miracle, then love has to be able to flow fully and freely through you before you can be miraculous, and that is NOT even remotely going to happen while you still have a ton of correction and purification to do. "Miracles are everyone's right, but PURIFICATION IS NECESSARY FIRST." Purification is a process of gradual shifting of perception towards truth and a LOT of it is needed FIRST BEFORE you gain access to the right to perform miracles.
MIRACLES ARE NOT SHIFTS IN PERCEPTION!!!!!!!!!
Miracles are expressions from love. To be able to express from love, you have to have willingness to allow love to be in you. You have to be aware of love, and you have to be free of blocks to love. That's a HIGH STATE of mind. That's advanced. You try to get someone who has just picked up ACIM and accepted a little bit of correction, to express God's love through them.
They will not be willing OR able, because there are too many blocks in the way. Miracle working DOES NOT come to the beginner. It takes a lot of undoing and correction of the mind - a lot of "shifts", which add up overall to a much bigger shift, which eventually put you closer to God and more in alignment with vertical perception, which THEN starts to reveal miracle working abilities. The ability to cause from above. To cause from above (super) the natural (ego horizontal nature).
If it does not PROVE and DEMONSTRATE that the ego's laws are not natural and do not APPLY at all, it is not a miracle.
And note that Jesus walking on water COULD have been considered a spectacle. However, the Course actually says, do not use miracles as a spectacle as an attempt to INDUCE BELIEF. This is often cut short. The end part is vital. If you use a miracle ONLY to try to "force" someone to "believe" or to become a follower or to go along with your teaching or whatever, to coerce, to manipulate them, THEN you are producing a (potentially spectacular) miracle for the sake of achieving an ego purpose. And this IS a mistaken understanding of their purpose.
But if you are not doing that, and you're not going around putting on a show just to shock and awe people, without using them to actually TEACH or HEAL or UNDO or RAISE THE DEAD so that people become MORE RESURRECTED, THAT is the only way that they are used incorrectly as spectacles. It's got NOTHING to do with whether the miracle is spectacular or not. And this idea of "not doing anything spectacular" has led people to hide in a hole and be afraid of miracles and to play them down and shove them in a box to suggest not doing ANYTHING that could be considered a spectacle. It's a gross misunderstanding.
So anyway. Stepping off my soapbox for now. Miracles are miraculous. This is a Course in SUPERNATURAL MIRACLES, ego-law breaking miracles, what appears "impossible" to the horizontal ego thought system, and expressions of real love which has the power to LITERALLY move mountains.
Come on people. This is a course in MIRACLES. MIRACLES!!!!! Not a course in fixing yourself up and sitting on a fence.