In Comus, the term “reason” means more than thinking in a rational and orderly way. Reason, for Milton, is the faculty that connects a person to God and separates them from the beasts. It is an essential aspect of God, and for humans, it acts as a divine, internal guide that must rule over the passions and appetites—a person’s “lower” nature—and thus allow the person to maintain a state of truth, virtue, and grace. Conversely, sin is associated with a lack of reason: with chaos, impulse, and violence.

This is why, when someone drinks the villainous Comus’s magic potion, their reason is overturned. As the Attendant Spirit explains, the transition from a man to the appearance of a beast involves “unmoulding reason’s mintage / Charáctered in the face” (Lines 529-30). He means that the process disfigures the likeness of God, the rational soul “minted”—that is, stamped on in the sense of engraved—on the human face by a higher power that embodies reason. Reason is thus the highest part of the human being. It is sovereign in the sense that it governs the lower powers of instinct and the senses. It is a gift from God; those who abandon it are rejecting their God-given nature. 

The conflict between reason and instinct is complicated in the masque by Comus’s ability to imitate reason in his temptations. Just before he encounters the Lady for the first time, he comments on his “well-placed words of glozing courtesy / Baited with reasons not unplausible” (Lines 161-62). This makes him a formidable enemy, which can also be seen in his ability to create a visual setting that maximizes the temptation by appealing to the senses with “dainties” and “soft music.” Fortunately, the Lady can resist. She is not fooled for a moment and knows exactly what Comus is doing. As a reason-filled soul, she is firm in her self-knowledge and her adherence to virtue and truth. She denounces Comus as a “juggler” (Line 757) who is trying to deceive her by “[o]btruding false rules pranked in reason’s garb” (Line 759)—that is, making specious arguments. The moral to be drawn is that the virtuous soul that maintains its connection to divine reason has nothing to fear from temptation or deceit, even when it sounds superficially plausible.

As a Christian virtue, “chastity” typically refers to sexuality: Someone who is chaste abstains from sexual activity outside of marriage. In Comus, chastity is synonymous with virginity since it is applied primarily to the Lady, and it signifies her broader virtue, which Comus proves unable to undermine. 

Elder Brother, who serves as the spokesman of enlightened reason and knowledge, speaks about the sacred power and value of chastity. He has the utmost confidence that his sister will come to no harm in the wood. Chastity is a “hidden strength” (Line 418): 

She that has that is clad in cómplete steel,

And like a quivered nymph with arrows keen

May trace huge forests and unharbored heaths,

Infamous hills and sandy perilous wilds,

Where, through the sacred rays of chastity,

No savage fierce, bandit, or mountaineer,

Will dare to soil her virgin purity (Lines 421-28).

His words suggest that chastity, like virtue generally, has a power that surpasses that of physical force because it ultimately flows from God.

Elder Brother’s confidence notwithstanding, the Lady’s chastity is endangered when she encounters Comus because he tempts her with his magical drink, which would result in her losing her self-control and participating in the drunken, licentious revelry that Comus’s crew indulges in. In his approach to the Lady, Comus relies on argument and persuasion rather than overt force. He does not explicitly threaten rape, although the possibility of sexual violence forms a subtext in the narrative. However, his goal is to corrupt, not simply to indulge his own appetites, so his primary tack is to erode the Lady’s spiritual resolve. He tells the Lady not to be cheated “[w]ith that same vaunted name Virginity” (Line 738) but to enjoy physical pleasure, “mutual and partaken bliss” (Line 741), before her youthful beauty fades over time. Comus thus challenges the Lady’s chastity with an argument about the need to make use of nature’s bounty. 

In her contemptuous reply, the Lady refuses to counter Comus’s argument directly since she believes that whatever she would say about the “sun-clad power of Chastity” (Line 782) and “the sage / And serious doctrine of Virginity” (Lines 786-87) would be beyond his comprehension. This proves her commitment to chastity but does not dispel the threat of sexual violence, which the circumstances of this scene, in which the Lady is physically helpless, make it impossible to completely dismiss. Also, the fact that the brothers storm in with swords drawn, ready to kill if necessary in order to free their sister, shows how serious they assess the situation to be. While the ending proves Elder Brother right when he said that “no evil thing that walks by night” (Line 431) can have “hurtful power o’er true virginity” (Line 437), it is also a means of sidestepping the question of whether the Lady would retain her “chastity” if she had in fact been raped, as historical norms surrounding women’s virtue often did not distinguish between consensual and nonconsensual sex.