Both Hamlet and the ghost condemn the relationship and marriage between Claudius and Gertrude as incestuous (1.2.157; 1.5.42). This was based on the Old Testament book of Leviticus 20:21:
”If a man shall take his brother’s wife, it is an unclean thing; he hath uncovered his brother’s nakedness; they shall be childless.”
It was interpreted to prohibit relations between the wife and the brother of the husband. It applied even after the death of the husband. In effect, upon marriage, the husband’s brother became the brother of the wife, and this relationship survived the death of the husband. As Claudius says:
“Therefore our sometime sister, now our queen, … have we …taken to wife.”
Claudius was in effect marrying his sister when he married Gertrude.
To Elizabethans, this doctrine of incest was not obscure canon law. It affected their lives, the throne and religion of England, and changed the course of history.
When Henry VIII was young, he had an older brother, Arthur, who was to become the next king. At age 14, Arthur married Catherine of Aragon, daughter of Ferdinand and Isabel of Spain. She was 17 at the time. Four months after the marriage, Arthur died. Catherine remained in England. Eight years later, when Henry became king, he decided to marry Catherine, who was 6 years older than he. There was concern about incest, since Catherine had been the wife of Henry’s brother. However, it was asserted that the marriage with Arthur had never been consummated, since Arthur had been sick, and there was no problem. As a further precaution, a Papal dispensation was obtained, and Henry married Catherine in 1509. Although Catherine became pregnant several times, all the children, except one, Mary, died in infancy or were stillborn. After 24 years of marriage, in 1533, Catherine was no longer able to have children. Henry was desperate to have a male heir, fearing another civil war over the succession to the throne. (See Shakespeare’s Henry VI Parts I, II and III, and Richard III). He decided to divorce Catherine and to marry a younger woman, Ann Boleyn, whom he believed could produce a male heir. As grounds for the divorce, Henry claimed that his marriage to Catherine was incestuous and void, since she had been married to his brother Arthur. Henry convened a court to try the matter, but Catherine refused to appear and appealed directly to the pope. (See Shakespeare’s Henry VIII). Henry realized that he could not prevail. Although a devout Catholic, Henry broke with the Roman Church and created the Church of England, which became Protestant. He obtained his divorce and married Anne Boleyn. She gave birth to a daughter, who later became Queen Elizabeth. Thus, the history of England, Europe and the world were affected by this concept of incest.