(Clearwisdom.net) "Sending forth righteous thoughts" is one kind of sacred tool that Master Li has given us so that we can use our supernormal capabilities to eliminate the evil forces that interfere with the Fa-rectification. Before sending forth righteous thoughts, we are required to eliminate all bad thoughts from our minds, bad notions and external interference, and imagine that we are like divine beings, as tall as heaven and incomparably noble, with enormous bodies. Our thoughts are pure and determined.
It appears to be simple and easy to do, yet it contains a deep Fa (Law) principle to further our improvement and advance us towards achieving Consummation: righteous thoughts are indestructible and Buddha nature has no omission.
While sending forth righteous thoughts at set times, we can keep a tranquil mind and pure and determined thoughts. However, at other times we become relaxed and return to the usual way of thinking of ordinary people. This is a manifestation of xinxing (mind-nature) issues and inadequate understanding of the Fa. Master Li said "In the past, whether people practiced qigong in parks or at home, they did it with much effort and dedication, and they practiced quite well. Once they stepped out the door, they would act differently and go their own way, competing and fighting with others for fame and profit among everyday people." (Lecture 1, Zhuan Falun) It is in fact the same principle.
Whether or not we are sending forth righteous thoughts, our minds should be righteous. This is because, even if our thoughts are only slightly unrighteous and have small omissions, the evil will make use of them to interfere. In the last stage of Fa-rectification, it is very important for our practitioners to cultivate to non-omission and to not give the evil any loopholes to utilize. I realize that the Fa principle implied in sending forth righteous thoughts requires us to strictly make sure our thoughts and mind activities conform with the xinxing standards of Dafa disciples at all time, and that we must use righteous thoughts and pure insights to guide our words and actions. Everything should be pure and righteous. If our righteous thoughts are indestructible, the Buddha nature will be without omission. At this time, all elements that are not righteous will have no room to exist.
Master Li said in "A Clear and Clean Mind" in Zhuan Falun that, "Everyone knows that Sakyamuni taught "samadhi." What did he teach prior to samadhi? He taught "precept" and abandoning all desires and addictions until nothing is left--then one can achieve samadhi. Isn't it such a principle? But "samadhi" is also an ability, as you are unable to completely achieve "precept" all at once. With the gradual abandonment of all bad things, one's ability to concentrate will also improve from shallow to deep." To keep the continuous righteous thoughts is the same principle as that of Ding (a state of empty yet conscious mind). We start from sending forth righteous thoughts at set times, and the purity and intensity of our righteous thoughts will improve as we send forth righteous thoughts more and for longer periods of time, and gradually our righteous thoughts will become indestructible. Master Li said, "However strong the righteous thoughts are, that's how great the power is." (Also in a Few Words) The stronger our ability to maintain righteous thoughts, the more powerful the righteous thoughts will be. Even when we don't purposefully send forth righteous thoughts, we can still have the effect of "the Buddha-light illuminates everywhere and rectifies all abnormalities" any time and anywhere.
By reaching the state of Buddha nature without omission, we will genuinely move towards Consummation in Fa-rectification. In fact, those Dafa disciples who have become undefeatable in the practice of Fa-rectification have accomplished this.
The above is just my personal understanding. Please kindly point out to me if there are any mistakes.