Tess of the d'Urbervilles: A Pure Woman is an exploration of the profound effects of naivete and gullibility on women in the 18th century who are shown to be at the mercy of men in all regards, even at the mercy of good men, like Angel, who is proven to be ironically named, not sincerely named: he is nothing like an angel. While Hardy wrote in the 19th century Victorian era, Tess is set in an earlier time as indicated from time to time in the text. Note below how Hardy uses passives and past perfect tense to describe a time before his own when cottages were torn down and cottagers sent from villages:
as the long [term] holdings [ended], [cottages] were ... mostly pulled down, ... [those who] were looked upon with disfavour, and the banishment of some ... who had formed the backbone of the village life in the past, [were forced] to seek refuge... (Chapter LI)
Tess is uniquely positioned to represent both upper class women and the "interesting and better-informed [village] class" of her father and mother. While in daily events Tess is of the craftsman's class, her impulses, unschooled intellect, and integrity are of the upper noble class, the ancient d'Urberville's class. To further Tess's positioning as universal woman, while Tess's father is a direct descendant of the d'Urbervilles, her mother began as a local peasant girl.
Hardy positions Tess this way, representing women of all levels of classes, to show the impact of externalities originated in men's behaviors (her father's drunkenness, Alec Stokes-d'Urberville's immoral manipulation, Angel's inconsistent philosophical application of moral principles) on naive, gullible, impressionable women's lives. As events unfold, Tess's experiences are applicable to all moral and pure women.
In summary, Tess is taken advantage of by Alec and, when she returns home to have her baby (a child whom Alec seems not to know about) without having accepted Alec's offers of marriage because she didn't love him and wanted to maintain her integrity, her mother and father forgive her, the villagers accept her, but she cannot forgive and accept herself. When her infant dies, she forces an exile upon herself to try to escape her own feelings of shame and impurity.
When at Talbothay's dairy farm, a place and work Tess loved, she gained a sense of dignity that did a lot to overcome the loss of her dream of teaching, which was removed from her by her father's drunkenness and Alec's tyranny. When Angel, no kind angel he, importuned her against her will, though she repeatedly said no, to be his wife, Tess learns the harmful effects that befall a woman from a good man's wrong behaviors as surely as from a bad man's wrong behaviors.
When Tess ignores her mother's plea that she keep her past to herself, Angel rejects her on their unconsummated wedding night even though, as Tess says, their secret sins were "just the same." When Angel leaves her to go temporarily to Brazil, she deepens her self-imposed exile and punishment by declining contact with Vicar and Mrs. Clare and taking a job as a farm hand in a cold, barren chalk-land farm. Even there Alec finds her and manipulates her, taking advantage of her father's death to hound her into despair and reunite with her. When Angel, ill and beaten down, returns, she retaliates against Alec's cruel taunts with murder. Then she and Angel flee until the executioner raises his black flag announcing her hanging, giving the ultimate picture of man's domination over naive but pure woman.
A few minutes after the hour had struck something moved slowly up the staff, and extended itself upon the breeze. It was a black flag. "Justice" ... had ended his sport with Tess.