In her classic study, Shakespeare's Imagery and What It Tells Us (1935), Caroline Spurgeon points out that, in Shakespeare's plays, evil and images of dirtiness and disease are strongly correlated:

She also adds that evil, thus manifested, appears to be contagious, infecting all that are touched by it: ‘the idea also that one evil leads to another is ever present with Shakespeare’. This concept of evil rests on the moral foundation of sanctity. In this chapter, I will examine the link between sin and dirtiness, disease or contagion in Shakespeare by looking at some key examples in King Lear, Timon of Athens, Othello, Richard III, Hamlet, Othello and Macbeth. I will also compare Shakespeare's sometimes gruesome descriptions of degradation with those found in the Protestant theology of Richard Hooker and John Calvin, who each provide dark visions of human impurity. I will also cross-reference Catholic teachings on sin as embodied in Thomas Aquinas. In the process, I will attempt to discover what was sacred to Shakespeare.

It has been the fashion in recent years to think about Shakespeare's many images of disease in the context of ‘a precise historical and medical moment’. For example, while Eric Langley is alert to ‘connotations of contagion: interaction becoming infection; communication becoming communicative; sympathy facilitating contagion’, in focusing so squarely on the early modern understanding of medicine, he appears to miss the moral dimension, even though this accounts for much of the process he describes. Likewise, Jonathan Gil Harris does a superb job of tracing contagion and disease in the discursive concepts of the emerging nationstate and mercantilism (especially as regards xenophobia), but he too never seems to think of his subject as a moral matter.