The Power of a Leniency to Show Honor of Torah

Gemara: Rav Huna said in the name of Rebbi: It is prohibited to insulate cold things on Shabbat (Rashi – to protect it from being warmed by the sun), But we learned in a baraita that Rebbi permitted it (Rashi – for we do not decree to prohibit this lest people come to insulate things to keep them warm)!? It is not a contradiction. The first statement (where Rebbi was stringent) was before he heard from Rabbi Yishmael in the name of Rabbi Yossi, whereas the baraita was said after he heard from Rabbi Yishmael in the name of Rabbi Yossi. For Rebbi was sitting and stated that it is prohibited to insulate cold things. Rabbi Yishmael son of Rav Yossi said: "But my father permits it!?" Rebbi responded: "If so, the elder has already ruled upon it [and I retract my ruling]."

Ein Ayah: The purpose of the entire Torah and all its details is to instill its holiness and the depth of its great value in the hearts of the nation of Hashem. Therefore, the details of the mitzvot are the aspects that are most clear, and through them the nation as a whole expresses their inner feeling of how dear and great the Torah is in their hearts.
On occasion, it happens that a certain leniency will be the medium to cause an overwhelming feeling of honor and sanctity of the Torah. It is not necessarily by means of the specific halachic ruling but from a more holistic understanding that brings the people to respect the Sages who have a fear of Heaven and to sense their great value. In such a case, it is fine for there to be a decision that leans, even surprisingly, towards leniency. For the leniency itself that is connected to the honor of the Sages will give this lofty feeling of dependence on a great rabbi in a manner that is equivalent to the practical impact of an act of stringency.
The leniency can be even more powerful than a stringency. This is because the stringency will be based only on the specific detailed case while giving honor to the Sages who ruled leniently and heeding their words is based on the larger value of a mitzva that includes the foundation of all of the Oral Torah and is the basis for the covenant between Hashem and Am Yisrael. This mitzva is the obligation to heed the words of the Sages.
Rebbi found a need to be stringent regarding insulating cold foods on Shabbat, in order to strengthen people’s appreciation for the lofty sanctity of Shabbat. However after hearing that Rabbi Yossi ruled leniently on the matter, he declared: "The elder has already ruled leniently." This came about because Rabbi Yossi saw fit that in his time this was the correct evaluation. Rebbi now ascertained that there was a judgement that was more inclusive (than the specific mitzva of Shabbat), and this leniency itself would bring an abundance of holiness for those who cling to it. For it would strengthen in the hearts of the nation their appreciation and honor of the Sages. This would result in life and bring a strengthened sense of holiness. That is why Rebbi declared, "The elder has already ruled leniently."