This was a very deep passage, rich with powerful metaphors, and here are a few thoughts.
First, how does thought indeed travel, like a boomerang? It seems to me that thoughts are preceded with and succeeded by vibrations. When some vibration comes up within my body and nerves, and I label it as a certain kind of feeling, certain thoughts arise in response. When I think certain thoughts, more feelings arise as a response, which are millions of atoms and molecules in my body vibrating in a certain way. Given that the environment around us is also full of such atoms and molecules, it stands to scientific scrutiny to posit that some of my inner vibrations will make a difference to the outer environment. Depending on the strength of these vibrations, others will pick them up from the outer environment and receive them within. At a very gross level, we see this happening through sound energy, when we speak and generate sound vibrations. These are picked up by others and processed for meaning and responded to. But at a subtle level, when I don't speak, I am still participating in this process of receiving and transmitting vibrations. Nipun pointed out that studies have shown how negative vibrations and positive vibrations left behind after a meeting can be picked up by people who come in a little later.
The second thought was on the claim that "This thought-world is more real relatively than this physical universe." The truth of this claim can be seen from our own experience. When I am totally engrossed in a thought activity, I lose perception of the world around me. I don't notice that I'm hungry or thirsty, that I need to go to the restroom, that it is hot or cold, etc. My perception of the universe is largely a result of the thought-world I am in, and it can and does trump what is so at the physical level.
The third thought, which I didn't share in the group to keep it short, was on the business of dwelling on an evil thought. The author has gone to the root of himsa (or violence) and explained how physical manifestations of violence are but a downstream expression of deep-rooted violence in the mind that happened much earlier. But, one question may be raised. When we meditate and observe our thoughts, both positive and negative stop bothering us. How is it then that by dwelling on the negative and receiving the same effect (of not being bothered by such thoughts), we end up on a very different path? I think the answer lies in the metaphor of "dwelling.' The word "dwell" means to live in residence. Effectively, it is about how and where we choose to confine ourselves. Observing on the other hand, is like being a traveler who passes through the dwelling while it is under construction, and notices the raw materials that are going into creating it. The observer is shocked by the non-realization of the dwellers that the materials are rotting, and will only lead to disease and infirmity. But the dwellers do not realize this - they are now used to the rot. Their seeming equanimity comes from the space of ignorance. The observer now has compassion for the dwellers - they do not see it as it is. But that compassion is also born out of ignorance, which is realized the moment the observer realizes that the observer and the dweller are one and the same. Then, the observer wakes up. There is no contradiction, and the author has used sharp words to drive home the distinction between creating a dwelling and observing the creation.
The final thought is on the third paragraph, where the author says that the best method to overcome depression is to think inspiring thoughts. Doesn't this fly in the face of instructions of meditation, where we are required to "not think" - and simply observe what happens? How do we reconcile the two ideas here? When I thought more about this, I realized that he isn't talking about any random positive thoughts (like watching a movie or going to a bar). He is talking about inspiring thoughts - we can only be inspired when we remember something about ourselves, and our sense of freedom increases. We recognize that power in ourselves through some trigger, be it a dualistic form of what some might call "God," or an attachment to what others might call "selfless service." When such an inspiration happens, the positive part of me develops the strength of a giant, crushing the negative which have now been dwarfed.
I remembered my time in a 10-day meditation seminar, where around the middle, I was having serious doubts about my ability to complete it. As I took a walk around the premises of the retreat, I noticed the tall trees that stood up to the scorching sun, without complaining, and didn't stop being true to their nature of giving shade. The lovely flowers which would often be covered by the dusty of our feet would not stop blooming - that was their nature and they would be true to it to the day they died. And here I was, not being able to recognize my own nature and complaining about this and that. At the next meditation session, I had been so inspired by the tree and the flower, that I call on them for help as my meditation teachers. As these thoughts multiplied, the negative thoughts on wanting to run away diminished, and were completely vanquished. Although my body was weak, I had never felt so strong before. I knew what the outcome of the next few days would be and there was no more trouble (there was still pain and all of the scary stuff, but it didn't scare anymore).
After remembering this, I realized that the author has shared with us a masterful insight of meditation. Theoretical meditation is about observing your thoughts, opening both the front door and the back door of your mind and letting the thoughts go through. Practical meditation is a battlefield! The forces of good and evil are stacked up against each other, and we must feed the positive so the negative is forced out. When the feeling of power and confidence has set in, only then will we have the strength to become an outsider in our own mind and observe our thoughts. We need an awareness of our inner strength to observe our mind, at the same time, the observation increases our awareness of our inner strength. They feed on each other.
I liked Guri's ending comment about the practicality of this idea.