William Shakespeare draws the story of Cymbeline from his sources and adapts them to heighten his own class bias-his persistent belief that gentle-borns possess much better human qualities than base-borns. Cymbeline is the epitome of Shakespeare's class view on the basis of the inherited blood quality. Many critics, such as Joseph Satin and Alice Griffin, have studied the sources of Shakespeare's plays. Yet they have paid less attention to Cymbeline than to other Shakespearean plays, perhaps not only because Cymbeline does not have an obvious primary source, but also because it is less popular with audiences. In his Narrative and Dramatic Sources of Shakespeare, Geoffrey Bullough lists many possible sources of Cymbeline. Most source critics, however, have generally agreed on the three sources: Holinshed's Chronicles for the historical material, The Decameron~ninth tale of the second day-of Giovanni Boccaccio, and the anonymous Frederyke of Jennen. for the heroine and the wager episode including the wandering scene. Accordingly, I choose these three sources in order to illuminate Shakespeare's class-oriented alterations of his sources. In modifying Holinshed's Chronicles into Cymbeline, Shakespeare intensifies the blood quality of the gentle-born, especially of the royal family. Shakespeare introduces into Cymbeline one type of royal blood-that is, the blood of Cymbeline's two sons, Guiderius and Arviragus. Their blood characteristics are of the highest sort in the play, but it is given little significance in Chronicles. In Chronicles, except for one definite gentle trait-bravery, we can hardly find any other high quality of blood possessed by two princes, whereas in Cymbeline Shakespeare adds other characteristics of gentle blood. The kidnapping is another creation of Shakespeare to show the two princes' royal blood. Chronicles does not say anything about the kidnapping, whereas in Cymbeline it is one of the major motives of the plot. The story of Cymbeline is mostly based on the two princes' kidnapping by Belarius. Another marvel of royal blood is Imogen. In Chronicles, Cymbeline does not have a daughter: he just has two sons, Guiderius and Arviragus. Shakespeare draws the heroine and the wager scene of Cymbeline from Decameron and Frederyke. Even though these two sources have heroines, they are quite different from Imogen. Imogen's chastity is also an effect of her royal blood. Shakespeare heightens Imogen's faithfulness towards her husband more than that of the above two wives, manifesting itself during the meeting with Iachimo. In addition, Imogen's unusual courage is another mark of her gentility. In Cymbeline Imogen not only shows no fear of death but also reveal no cowardice. When she knows that Posthumus commands Pisanio-his faithful servant--to kill her, Imogen courageously accepts it, though she is not guilty of infidelity. The fragrance of the bed chamber further highlights Imogen's noble blood. Shakespeare deliberately distinguishes the gentle-horns from the base-horns by their smell. The two sources of the wager episode do not mention any kind of odor. However, in the bedroom scene of Cymbeline, Shakespeare introduces the perfume to show Imogen's royal blood. Finally, the wandering scene of Imogen also reveals her royal blood. The two sources which have Imogen's counterparts-Decameron and Frederyke---contain no remarks about the two heroines' blood quality. Consequently, in Shakespeare blood quality determines one's character. In Cymbeline Shakespeare distinguishes gentles, especially royals, from base-borns on the basis of their inherited blood qualities. He endows gentle-horns with noble qualities of blood, such as intuitive knowledge, extraordinary courage, fidelity, sweet breath, and so on; however, he does not give these admirable characteristics to base-horns. Moreover, whereas betters are eventually rewarded, base characters are never rewarded because Shakespeare believes that base qualities do not deserve any recompense. In this play Shakespeare's class-consciousness determines his modifications of the sources. He deliberately modifies their stories and characters according to his blood-consciousness, This theme not only gives the play much more strength and variety, but also more subtlety and sophistication than the three sources.