One is not unoccupied because one is absorbed. There is visible labor and invisible labor. To contemplate is to labor, to think is to act.
Hugo defends the inner life as real work. He pushes back against the idea that only physical effort counts, and he calls thinking a form of action. The repetition sets up pairs that mirror each other: visible and invisible, contemplate and labor, think and act. In the novel, this matters because so many characters are judged only by surface labels: convict, beggar, officer, girl. This line insists that the unseen parts of a person are also the truth of them. It can resonate with readers who process quietly, who heal slowly, or who do not show their struggle in obvious ways. The quote honors interior effort as dignity.