Noach

At the conclusion of the flood which essentially destroyed the world,  Noach is commanded to leave the Ark with all the people & animals that were saved to go out & rebuild the world. 

Noach then built an altar & offered animal sacrifices to Hashem. וירח ה את ריח הניחח ויאמר ה אל לבו לא אסף לקלל עוד את האדמה בעבור האדם כי יצר לב האדם רע מנעריו ,‎and Hashem smelled the pleasing aroma, and Hashem said in his heart, I will not continue to curse the ground because of man, for the design of man's heart is evil from his youth. 

There are a few things in this posuk that make one wonder. First, Hashem had just saved Noach & his family from being destroyed with the rest of the world. When the ordeal was over, Noach brought a sacrifice. What was so special about that that Hashem said he would never destroy the world again? How does the reason that the design of man's heart is evil from his youth relate to that? Was the reason because Hashem liked the korban, which is man doing good things, or is it because man was born evil , so it's not in man's control? Therefore, Hashem won't let it affect the world?

Ramban states that Hashem is speaking in man's defense saying, since people are created with an evil nature, it would not be proper to destroy the world because of them. Ohr Hachaim also interprets the posuk as such. He even compares man to a bull trained to perform in the arena who is not put to death if it gores & kills a person even in a non-sport setting. Since this is what it was trained to do, we don't view the bull as intrinsically bad; rather it killed as a result of its training.  So, too, when man sins, it's not because of a conscious decision to do evil; rather it's because that's what is inherent in the nature of man.  

If that's the case, then what changed after the flood? Why did Hashem just decide now that it's not man's fault & again, what did it have to do with the sacrifice that Noach brought?

Reb Chaim from Brisk was once walking with his students on the street when they saw a wagon driver who looked totally exhausted, weak and slumped over in his wagon, barely able to move.  Yet, when he hit the horses, they went to the left or right as he drove them. Reb Chaim turned to his students & said, “isn't this amazing? The horses are healthy, fit & strong, much more powerful than the driver. With one good pull, they could free themselves of the wagon yet they still stay & are in control of their much weaker master. 

Reb Chaim continued; while the horses have much more power than the driver, that's all they have, power but no brain.  They are horses & can't think; they don't know how to exercise their power for their own benefit. אדם ביקר ולא יבין נמשל כבהמות נדמו ,A person gets from his creator tremendous power to do good; however he doesn't realize or understand the power he has. Therefore, he's compared to these horses who also don't  know the power they have ‎. 

We know that there are two types of teshuva. There's teshuva out of love & teshuva out of fear. Teshuva out of love is much greater, because one is not repenting because of fear of getting punished, but rather because one has a love for Hashem. Another difference between teshuva out of love or fear is that if one repents out of fear of punishment, then one could rationalize in his head what he's doing is OK. That diminishes the fear aspect because one will say that Hashem will understand; it’s not so bad.  In his head he thinks there will be no punishment & he could get away with it. 

However, if one does teshuva out of love then there is no rationalization because when one does something out of love, he will make sure that the one he loves isn't getting hurt; when there is love, one will be so much more careful not to mess up. 

Perhaps this can explain our dilemma. Before the flood, the people were like the horses, not realizing that they had the power to overcome the inherent evil that every person is born with; that's why they led the world into total decay causing Hashem to destroy it.

When Noach was saved, the first thing he did when he came out was sacrifice to Hashem, displaying a love for Hashem. Once Hashem saw that Noach was sacrificing to Him out of love, then Hashem recognized that if man felt a love for Him, then they could break the natural tendencies for evil & use their power that was placed in them to overcome evil & do good.That's why when He smelled the korban that Noach brought, He decided that he wouldn't destroy the world again. 
The key is to focus on our love for Hashem & then, instead of acting like the horse with no clue to what we could accomplish,  ‎we will be able to reach the ultimate heights of getting closer to Hashem!