On the first day, I settled down with Harper Lee's second book, Go Set a Watchman, which read like a draft of her first. Both novels dive into the traumatic legacy of America's nation-changing original sin of slavery. But while Watchman is flecked with gold, To Kill a Mockingbird is a national treasure.

On the second day, I read, for the third time, Mockingbird.

Mockingbird is personal. I didn't realise just how much until my latest reading. My Australian parents brought me up, for a short time, in Durham, North Carolina. I only have about a dozen memories – which are the earliest of my life – from North Carolina.

The Easter Egg treasure hunt, in probably my first year at school, is a strong memory. I looked at a black teacher and thought, "She's very black." Thinking back, it was a judgment as loaded as, "Her hair is long," or "She has a blue hat."

I will add here a Durham memory of my mother's. She was there the first time that I was close to a black person. A black messenger boy arrived at our door with a parcel. I opened the screen door for him, went closer, gently stroked his hand, and then looked at my finger – obviously, my mother says, to see if any colour had rubbed off. She was about to jump in with a friendly explanation but realised it was not needed. On reflection, she said the messenger boy seemed "quite chuffed" at how calm I was about going close to him. She thought, "Now I know that white children are not born with a different attitude to black people than to white."

My life in the South in the late 1960s and early 1970s was in stark contrast to Scout's in the 1930s. Despite that, it was only after my latest reading of Mockingbird that I had an epiphany: every time I had read or thought about the book I had been visualising scenes, for the parts set in Scout's immediate neighbourhood, from North Carolina.

Whenever Boo Radley's house was mentioned I pictured the home of the neighbour of my best and older friend, Henry. Every day this neighbour sat with his leg propped up in front of him – looking intimidating – in a cloud of smoke. My mother said he had been hurt in a place called Vietnam.

When Atticus shot the dog I saw him fall in the Vietnam veteran's front yard, and I remember how Henry's father shot the raccoon in my back yard.

When Jem takes Scout to her first day of school I see Henry walking me to my first day of school.

On the night of Jem and Scout's "longest journey together" I see them being attacked under a tree in the Vietnam veteran's back yard.

I also see the porch of the house opposite Henry's where Miss Maudie tells a distraught Jem that Atticus never had a hope of winning the case but "… he's the only man in these parts who can keep a jury out so long in a case like that. And I thought to myself, well, we're making a step – it's just a baby step, but it's a step."

How did I miss the fact that I had been picturing North Carolina for hour after hour? Maybe our early memories are ever-present but invisible backdrops that shape us more than we know. My mundane personal experience points to a key theme of Mockingbird– we can be blind to the obvious.

Miss Maudie assured Jem that some people, apart from the black folks, had tried to help Tom Robinson. But it is clear that when it comes to race most of the white community, with exceptions such as Miss Maudie, cannot see. While I was oblivious to my first memories entwining themselves with Scout's world, Miss Maudie would have spotted them straight away.

In a similar – but more dramatic – way, can we expect a jury member at the rape trial to see the racial culture he had bathed in since birth? Even Scout is not immune to its insidious power. When her friend, Dill, cries because the circuit solicitor called Tom Robinson "boy", she says, "Well, Dill, after all he's just a Negro."

My weekend in Maycomb County gave me a deeper understanding of Mockingbird. That would not have happened without the release of Go Set A Watchman and the accompanying controversy, including that an older Atticus was racist. It made me wonder, uncomfortably, how fair it was of me – who grew up never hearing anyone spit the word "nigger" – to judge the racists of Maycomb County. I had not spent time in their skin. I had not worked in their pigpens. I had not eaten poundcake on their porches.

While Lee uses a twenty-six-year-old Scout in Watchman to harangue us with her message, by the time she writes Mockingbird, she has taken Scout back to her childhood innocence. Young Scout takes our hand – as she did with Boo Radley at the end of her journey – to show us everything, even things she does not yet understand. We wrestle with our conscience far from judging eyes. Lee (or her editor), had wisely decided to discard the whip and offer us syrup.

Watchman was a step in the right direction of the masterpiece that is Mockingbird. Just a baby step, but it was a step.

Rob Ashton is the chief comment moderator for Fairfax Media. He looks forward to reading and responding to your comments about Harper Lee's opus.