The Torah states that after having spent many long days in the תיבה protecting himself from the powerful rains of the Mabul, Noach and his family are finally instructed to leave the תיבה (בראשית ח;ט"ו,ט"ז). But why was it necessary for Hashem to issue Noach an explicit directive to leave? Once, as we are told, Noach had removed the cover of the תיבה and noticed that the earth had dried up (שם פסוק י"ג), why would not he and his family immediately emerge from the תיבה on their own, even prior to receiving a directive from Hashem? Ibn Ezra (שם) suggests that Noach's hesitancy was due to the fact that the ground was obviously quite soft because of the rain, and it would be difficult to walk upon it. Hence, Noach needed the assurance of Hashem that it was in fact safe to disembark.
One can, however, suggest that Noach's hesitancy was rather related to his mind-set at that moment. The world and civilization as Noach knew it had ceased to exist. Thousands perished, and no trace of their existence remained. Noach was suddenly overcome with feelings of shame, embarrassment, guilt, and helplessness. He wondered whether there was any purpose in perpetuating life. If Hashem could wreak such havoc on the world once, He certainly was capable of doing it again. As is well known, there are those opinions among Chazal who never viewed Noach very positively, as cited by Rashi at the beginning of the Parsha (שם ו;ט בד"ה בדרתיו). He was certainly not terribly successful in eradicating the wickedness and evil behavior of his contemporaries. Perhaps, he felt, he was partially at fault for what had transpired. Noach thus delayed his exit from the תיבה as if to suggest that life on earth was not worth continuing. He thought that perhaps he and his family might just as well die on the תיבה.
Hashem, however, decreed otherwise. He urged Noach on, and told him not only to leave the תיבה, but to be fruitful and multiply on earth (שם ח;י"ז). Man can learn from his mistakes and rebuild the entire world. That is actually his mission, and he therefore cannot despair. It is this theme that one may suggest is echoed in the Tefillah of "Zichronos" recited during Mussaf on Rosh Hashanah, where we make reference to the fact that Hashem remembered Noach, and ultimately made him the ancestor of all of mankind. Not only did Hashem physically spare Noach, but He also gave him the impetus to overcome even the destruction of the rest of the world. When Noach finally left the תיבה, he did indeed succeed in rebuilding the entire world.
Many people in this century, it would seem, have fortunately understood this lesson very well. Many of our grandparents and other relatives lived through the horrors of the שואה, during which many may have concluded that the Jewish world was coming to an end. Many indeed were unable, unfortunately, to leave the spirit of the camps and the suffering behind them. Fortunately, however, most mustered the necessary courage, having heard Hashem command them to leave the "תיבה," to walk away from the Holocaust, in order to rebuild Judaism both here and in מדינת ישראל. It is their courage and efforts which have resulted in the rebirth of vibrant Judaism in many places throughout the world