Following the completion of the מבול Hashem commands Noach צא מן התיבה אתה ואשתך ובניך ונשי בניך אתך. Prior to the מבול Hashem commands Noach ויאמר ה' לנח בא אתה וכל ביתך אל התיבה. Before the flood Hashem tells Noach and his family to enter the תיבה and after the flood he tells Noach and his family to leave the תיבה. The Midrash writes that Noach would never have done anything without Hashem telling him what to do. The Ben-Yosef asks if Noach would dare to act on his own before Hashem told him to, following such a great tragedy as the מבול. However, on the contrary, one can ask why would Noach have to be told to leave the תיבה? After the water subsided would it not be logical for Noach to leave the תיבה and rebuild the world?
The Ben–Yosef answers his question by saying that the Midrash is trying to teach an important lesson. One might think that the reason Noach entered the תיבה was just to save his life. However, now that the מבול has ended, and Noach is able to walk on dry land again, he might not recognize the Chessed of Hashem. It is comparable to one who leaves jail and wants to start a new life again. It is unlikely that he will go back and remember his old life. The same is true with Noach. One might think that once he left the תיבה and started a new life he would forget his past. Therefore, the Midrash comes to teach us that Noach did not forget his past and would not act without Hashem’s direct command.
Harav Yosef Adler provides the answer to the second question. He answers that after the destruction of the world Noach did not know if it was worth it to rebuild the world if it could get destroyed again. Therefore, Hashem needed to tell Noach צא, go out and rebuild the world. צא was Hashem’s encouragement to Noach not to give up and that if he rebuilds the world it will not be destroyed again. Hopefully we can take these two messages, not to forget our past and never to be discouraged, and build a nation of true Bnai Torah.