Those words are spoken by Marcellus (Michael James Shaw) in episode three of Roots, and they are all the explanation you need about why the biggest miniseries in television history has been remade 40 years after the original.

Marcellus is ostensibly a free man in the American south of the early 1800s, but all around him is a state apparatus that contrives to remind him he is merely on probation. At any moment, his liberty could be taken away. So, too, his life.

It would be melodramatic to suggest this is the world in which African-Americans still live more than 150 years after slavery was abolished – if we didn't have incidents like the Philando Castile shooting to prove otherwise. For black and white Americans alike, the shameful legacy of slavery lives on.

Roots isn't preachy about this. Nor does it go out of its way to make the links with the present day. It's just that they're hard to miss.

The original series, based on Alex Haley's semi-factual novel, came at a time when black America seemed poised to reap the rewards of decades of civil rights struggle. And it resonated: the last of its eight episodes was watched by 100 million people, a record that still stands, in 1977 (the best a show can hope for these days is around the 14 million mark).

This new version is four two-hour episodes, each made by a different director. Australians Phillip Noyce and Bruce Beresford helm the first and last, African-Americans Mario Van Peebles and Thomas Carter take episodes two and three. The narrative remains essentially the same, but the treatment – and the graphic violence – is very much of the moment.

Noyce kicks things off in the Gambia in West Africa, where Kunta Kinte (English actor Malachi Kirby) is on the brink of manhood. He is working his way through the rites that will initiate him as a warrior of the Mandinka tribe. He is a Muslim (not an element I remember from the original, but treated in a no-big-deal way here) and a bit of a rebel: his father wants him to carry on the traditional ways, he wants to go to university in Timbuktu. But when he is captured by a rival tribe and sold to the English as a slave it all becomes moot.

The Middle Passage to America is horrendous – the slaves are chained supine to the floor, left to choke on the reek of excrement and their own vomit (these scenes remind me of Steven Spielberg's Amistad, an overblown affair in some respects but impressively brutal in its depiction of the conditions on the slave ship). On board, there's an attempted revolt that comes to a predictably grisly end. Brilliantly staged and filmed by Noyce, with a surprising use of music, it is one of the outstanding moments of a strong episode.

America offers no respite: Kunta Kinte is sold to the Waller family as a plantation slave, given a new name, Toby, by the lady of the house, and whipped into submission for refusing to take it.

That was one of the most memorable scenes 40 years ago and it remains so here. In fact, if there's a weakness in this supremely powerful series it is that the memory of the first remains so strong, at least in its key moments.

But despite those massive viewer numbers back in '77, not everyone saw Roots, and the generations who came after may never have even heard of it. Meanwhile, America convulses over police shootings of black men, and reprisal shootings of police.

We shouldn't need this Roots, but we do. We should be thankful it's so good.

Roots premieres on SBS Wednesday July 27 at 8.30pm

Karl Quinn is on Facebook and on twitter @karlkwin