There is a very important lesson, one which is extremely relevant to every one of us, that can be learned from the life of Rabbi Shimon. We find in the Gemara that as much as Rashbi was considered amongst the greatest of the Tannoim even before his harrowing, thirteen-year ordeal in the cave, he emerged from there on an unfathomably higher and holier level. It is clear from the Gemara that Rabbi Shimon considered the suffering he endured during that period to have been the direct cause for his greatness and divine revelations in Torah.
The famous Gemara in Shabbos (33b) which relates the entire episode of Rabbi Shimon and his son Rabbi Elazar needing to run away and hide from the Romans, and their subsequent thirteen-year ordeal in the cave, also relates the following episode regarding his emergence from this painful ordeal:
When Rabbi Shimon finally got the all-clear to leave the maarah, his father-in-law, Rabbi Pinchas ben Yair, heard the wonderful news and went towards his holy son-in-law and grandson in greeting. He immediately noticed that Rashbi was covered in terrible wounds, and his skin was painfully damaged as a result being exposed to sand, earth and stones as a replacement for clothing for thirteen years. Upon witnessing this pain, R' Pinchas cried tears of distress which fell upon the open wounds of Rashbi and further exacerbated his pain. "אוי לי שראיתיך בכך", "Woe onto me that I see you thus", R' Pinchas exclaimed in anguish.
In response, R' Shimon joyfully exclaimed אשריך שראיתני בכך שאילמלא לא ראיתני בכך לא מצאת בי כך, "Fortunate are you that you see me thus, for if you would not see me thus, you would not find me in this situation".
Which situation was R' Shimon referring to when he said it's fortunate that he had gotten to that stage?
The Gemara continues to tell us that in the times before R' Shimon had to go into hiding, whenever he would ask his father-in-law a question in learning, R' Pinchas would answer with twelve explanations. Now, upon his emergence from the maarah, R' Pinchas would pose a question and R' Shimon would provide twenty-four responses. This was the fortunate circumstances that came as a direct result of his immense suffering, and his subsequent immersion in Torah while in the maarah.
So, we sing in the famous zemer of Bar Yochai: בִּמְעָרַת צוּרִים שֶׁעָמַדְתָּ, שָׁם קָנִיתָ הוֹדְךָ וְהַדָרֶךָ, "In the stony caves where you stopped, there you acquired your glory and your strength". It was the suffering in the caves which were the impetus for his acquisition of a Divine growth and glory.