How are we to understand this gemarah? After learning for 12 consecutive years in a hidden place from civilization, sustained daily with a meager portion of carob and water, engrossed totally in learning Torah, they rose to such a spiritual height that their fire burnt up anything that was not on their spiritual plateau. How then by spending another year in the same intense spiritual state and delving even deeper in the Torah connecting to Hashem, did Rabbe Shimon become more mellow and less destructive than before?
We can answer this with another gemarah (Baba Basra 134, Succah 28). Hillel had 80 talmidim of whom Rabbe Yonasan Ben Uziel emerged as the greatest. When he would learn Torah, the fire that arose from his learning would incinerate a bird that was flying over his head. The meforshim ask that if this was the super power of Yonasan Ben Uziel how much more so must have been the power of his Rebbi. If so what happened when his Rebbi learned Torah? The Kotzker Rebbe answered nothing would happen. His greatness was that he was able to control the fire that it would not even appear on the outside. A similar story was said about the Vilna Gaon. Rav Chaim Voloshin’s brother Zalmeleh was recognized as a fiery malach. His zerizus was beyond off the charts. Rav Chaim said that the Vilna Gaon was on this very madraigah when he was only 13 years old. The difference was he was able to contain his fire and no one was aware that he possessed it.
It the sefer Sheim Hagadolim it is written that the Ari Hakodash in the Sefer Gilgulim writes that Hillel was a gilgul of Moshe Rabbeinu. Both were described as incredibly modest (Sanhedrin 11Shabbos 31bהוו ענוותן כהלל ) both lived 120 years, the four last end letters of the Torah משה לעיני כל ישראלspells הילל. According to the above we can suggest that Hillel and Moshe shared another aspect together and that is that when Moshe Rabbeinu descended from Har Sinai with the second Luchos an incredible light shone through his face and he concealed it with a מסוה. In this aspect both excelled with incredible modesty not to let others know of their greatness. The gematriah of מסוה is אלף hinting to the small aleph of the word ויקרא which attests to Moshe Rabbinu’s humility. Only those who conceal their greatness possess the middah of ענוה .
Rabbe Shimon and his son excelled so much in devaikus with Hashem and Torah learning that the fire of Torah was like that of Yonasan Ben Uziel and maybe even more. However, it was not controlled and disciplined. It was only through spending another year steeped in the same inyanim was Rabbe Shimon alone able to penetrate an even deeper and loftier level of Torah where he was able to control his fiery Torah. Not only was he able to control his holy fire not to destroy, but he was also able to heal what was destroyed by Elazar his son. Rabbe Shimon achieved the higher level of Torah learning. בר יוחאי someone who is able to give life instead of taking it away. Someone who is able to compliment instead of criticize as we see from the next story of Rabbe Shimon when he meets another Yid Erev Shabbos carrying two bundles of haddassim one for zachor and one for shamor and he complimented Am Yisrael for their love of mitzvos. Someone who possesses a good eye instead of a bad eye on others. Someone who controls his mouth and speech building people with them instead of making them feel like dwarfs or unworthy. Someone who controls his anger and pain, making them unnoticeable to others.
All this stems from someone who has reached the deepest level of עץ חיים of Torah learning, like Rabbe Shimon and therefore is able to giveחיים to others in so many positive fashions, emulating his creator in as many ways possible. Such a dramatic change can take place immediately if he can reach the עץ חיים of Torah.