The gemara (Kesubos 77b) relates that R' Shimon bar Yochai greeted R' Yehoshua ben Levi in Heaven with the question, "Was a rainbow seen during your lifetime?" The rainbow is the sign of Hashem's promise to Noach not to destroy the world again. RSHb"Y was trying to gauge the level of tzidkus of R' Yehoshua ben Levi -- did his generation need to invoke the promise of the rainbow to escape punishment, or was RYb"L's own tzidkus enough to protect them?
R' Yehoshua ben Levi replied that rainbows did appear during his lifetime (in truth there weren't any, but R' Yehoshua ben Levi did not want to openly reveal his tzidkus). RSHb"Y replied that if so, R' Yehoshua was not really the son of the great R' Levi, his father -- RSHb"Y was in effect calling him a disappointment.
RSHb"Y's test seems at first glace to be quite harsh. As great as any one tzadik's merits are, he is but a single individual. The gemara tells us that there were tzadikim who were worthy of receiving ruach hakodesh but were denied that gift because they lived in a generation that was not worthy of such a level of hashra'as haShechina. Why did RSHb"Y find it so unimaginable that R' Yehoshua ben Levi was a tzadik of the highest calibar but despite his great personal tzidkus, he lived in a society that still needed that rainbow to ward off punishment?
"Kol she'lo nivneh Beis HaMikdash b'yamav k'ilu necherav." Here too, even tzadikim seem to take the blame for the Beis haMikdash not being rebuilt in their lifetime, as if they could single-handedly bring it about. The Kozhnitzer Maggid quotes the Alshich as explaining that the key word in this teaching of Chazal is "b'yamav." It should not be translated as "in one's days," but rather as "with one's days." Each and every person's day to day actions contribute (or c"v the reverse) in some way to the ultimate rebuilding of the Mikdash. Of course no one individual can do it all. What every individual is responsible for is doing his/her part to the utmost.
RSHb"Y was not asking R' Yehoshua ben Levi whether his merits removed the need for the rainbow for the entire world. He was asking, "Nira'sa ha'kashes b'yamecha?" -- Have you, R' Yehoshua ben Levi, done all you could with your own time, your own days, to obviate the need for that rainbow?