The correct answer is: "The first step, in the wrong direction, was the violence done to nature and to conscience, in arresting the benevolence that would have enlightened my young mind."
In this phrase, the author is clearly stating his position towards the whole act of enslaving people. He describes it as "a step taken in the wrong direction" as it is an activity that inflicts the "violence done to nature". By saying this, the author blasts slavery and labels it as a dreadful act that goes against the correct behavior of human beings.