On Reincarnation
Reincarnation is the exoteric degeneration of the Noble Truth.
From my honest point of view, there has hardly been any concept that has done as much damage to the post-Christian West as reincarnation. We can define it in many ways, I personally consider it the triumph of the ignorant exotericism of modern minds over the noble truths that are hidden in their original sense. I do not consider myself an expert, but I will try to give my point of view on said "spiritual fashion" of this Godless society.
First of all, it would be necessary to define the bases of modern perception when we speak about "reincarnation". As many of you may suppose, it is about the same soul going through different bodies, the same spiritual essence going through different lifes, roughly explained. Let's go by parts.
This concept is totally wrong. Even imagining this concept to be admissible, it would not be the goal or fit with the goal of any traditional Buddhist, for example. For any aspiring Tibetan monk, he must know (and he surely knows) that the soul must be "destroyed", or rather dissolved in the atman, after being in a state of certain spiritual ecstasy, the atman must merge with the brahman in order to achieve that "new life" or rebirth as the Buddha called it. This shares similarities with Christian theosis, when the monk has to empty his soul so that God can enter it, as has been described by mystics such as Saint Teresa of Avila.
We therefore see that reincarnation, just as modernity has deformed its original concept, now has nothing to do with what it intended to teach. Even so, let's make an effort and take for false the precepts that we have previously established. How then could the falsity of reincarnation be proved? The angelic doctor did not argue directly against reincarnation, but he did prove the impossibility that a soul can unite with different bodies; "human souls do not differ from each other in species, but rather in number; otherwise, the men would not all be of the same species."
But the difference that comes from the number comes from material principles, thus the difference between human souls must be taken from something material. Therefore there is a way that matter departs from the soul itself, since the soul is an intellectual and not a material substance. Thus, we have to affirm that, according to the different matters to which souls are united, this is how their diversity and plurality becomes.
We also have to bear in mind that the soul joins the body as a form. These forms must be proportionate to the matters, since they are mutually related as power and act, and every act responds to the same power. This shows that a soul cannot be united with more than one body. The force of the motor must be proportionate to the instrument itself, as not just any force moves any instrument. However, the soul, even though it is not a form of the body, cannot be said to be the motor of the body; we distinguish the animate from the inanimate by sense and movement. Therefore it is necessary that according to the various bodies there are different souls.
Catholic doctrine also agrees with this truth. Thus the psalm says: "He who uniquely created their hearts"; because it means that God created each soul separately, but not all at the same time, nor did He determine one for several bodies. In the same sense it is also said in the book "On ecclesiastical dogmas": "We affirm that human souls were neither created in the beginning with the other intellectual natures nor were they all created at the same time." Let us also remember the distinction that saints made like Saint Jerome between soul and spirit, which does not support the idea of reincarnation, but quite the opposite, since it supports the Thomist position that each soul was uniquely created by God.
So if reincarnation is a misconception, what did the original Buddhists say about it? As stated at the beginning, Buddha never taught that a soul could unite with different bodies, but rather the advancement of the body to different spiritual states, something that is quite different from what the people of the post-Christian West believe. Just as the atman wishes to unite with the brahman, it is impossible for him to unite with another atman.