In this verse drama, John Milton endorses the importance of virtue. His primary themes include chastity, a trait he presents as crucial for women, and temptation, which he argues is difficult to resist because the devil makes it so attractive. The masque form (a type of elaborately costumed, formalized presentation) is suitable for these themes, as he employs stock characters whose purpose is to embody archetypes that illustrate his messages rather than to show character development.

For Milton, human virtue is never a given; he wrote often about the contest between good and evil. The unnamed Lady, who is lured by many temptations but never succumbs to seduction, manifests his concern for chastity. For women, Milton argues, virginity accompanies moral rectitude. The literal setting of the woods, and the fairytale-like trope of getting lost there, is used to establish the juxtaposition of Lady’s innocence with the knowing ways of the lecherous Comus. While this character is connected with traditional Greek mythology, Comus's characterization is primarily Milton’s invention.

Comus, although obviously embodying many sinful practices, disguises his true character by assuming the visage of a boy with an affable demeanor, who offers many comforts to the lost Lady. Appearances can be deceiving, Milton emphasizes; the devil does not make his true self visible immediately, if at all. Initially fooled by his friendliness, Lady soon finds herself confined in his castle and sorely tempted by many earthly delights.

For Comus, physical assault would not accomplish his true purpose; only if Lady willingly gives in to his advances can he truly conquer her, as his goal was to corrupt her. Although her brothers find her and help her leave the castle, their actions are a physical but not a spiritual rescue. By resisting evil to the end, Lady proves herself both chaste and steadfast in her principles.