Hope you like metaphors
Throughout Part One in Song of Solomon, we see Milkman begin to chafe under his father's image. It makes him feel like he can't ever make a name for himself, because there is always a long and dark shadow cast by his father that makes it impossible for him to form many lasting friendships in his home town. Striking off on his own, Milkman steps out of this shadow, only to find himself in a larger one cast by his grandfather Macon I. While we start to see Milkman begin to embrace these shadows, I don't think he realizes just how important to his life they are.
Milkman has not only struggled under his father's shadow, he also lived under it. What this means is that he has - whether for good or for ill - inherited some of his father's mannerisms. Unlike his father, though, he did not work for them, and does not understand their limitations. This has never been a problem for Milkman, however, because he has always stood in his father's shadow, which makes anything he does seem small comparatively, and he hasn't been able to develop the proper boundaries necessary for human-to-human interaction.
One person that attempts to clear things up with Milkman is Lena, who lays it out, plain and simple, for Milkman to see. This shadow, however, covers the table, and he gets nothing out of it, except maybe the kick out the door.
His limitations become inherent whenever he strikes off on his own. Milkman feels he is stepping out from under his father's shadow, but doesn't realize he stepping out form his only protection from the Sun sitting just outside. The reason he doesn't have problems immediately when exploring is that there is another shadow waiting for him: Macon I's. This larger shadow "covers for him" while in Danville, as the whole populace only remembers Macon I as practically a legend. This makes them fairly helpful towards Milkman as he tries to find the gold, and confirms his thoughts on how people should treat him.
His main problems start when he hitches a ride with a stranger and acts as he always had. By this point, Milkman doesn't understand the difference between shadow and light, as stepping outside of his grandfather's shadow blinds him into darkness. He acts as he always had, and in return obtains a previously friendly man's hostility. This makes him blink, but it's not enough to make him regain his vision.
This persists into Virginia, where he promptly gets into a knife fight because of his overinflated sense of wealth. This angers the people who have always lived in the Sun, because certain things you just don't do, Milkman has done. This time around, though, Milkman realizes something is up. He begins to guess at the causes, but turns a blind eye towards the glaringly obvious one: the fact he was born into money. We finally see, though, that as Milkman learns more about his past, little by little, his eyes are opened to how he acts towards his family and (hopefully) other people as well. The table Lena laid in front of him is brightening, and he can see more of what he is doing wrong.
Hopefully, near the end, we see a near complete Milkman with the knowledge of how much his family means to him, not only in how he got where he is, but also how they could and did affect him throughout life.
