"The Small Holding the Heartbeat of the Large"

That Ahab's wife should be named Una is very fitting, a name that captures the unity of traits which she embodies.

We have already discussed that Ahab is split, and the story of Ahab's wife explains this split as one of reason and madness. According to Ahab, madness and reason are two extremes of one, but the men in the tale cannot hold both of these extremes in one body. Ahab may succeed in doing so for a short while, but it becomes clear in the "Birthing Room" chapter, in which his vengeance is born (and which Una later explains to Justice that he loves like another son), that he will descend into madness.

Una is different. She is both angel and devil, as she explains, both madness and reason, as Ahab says ("You have it (madness) in you"). Her reason does not allow her to fall to her knees like the commoners before Gabriel's false prophecy, but her madness (which she takes upon herself when she enters the birthing room) causes her to do so when she believes he is dead. Her reason allows her to dismiss Elijah, but her madness, symbolized by the loss of language she suffers after parting from Ahab, causes her to bite her tongue until it bleeds. 

Una's oneness, the balance she strikes between reason and madness, allow her to function as Ahab's supplement, to both understand his madness and balance it with reason. For this reason she is allotted masculine traits - those of the phallus, of language, and of power. When Ahab first tells her he has been "dismasted", she immediately sits up "erect". When his letter comes, mad words without a voice, she holds it to her throat "as though to give it voice". She explains the word "ardor" to her son, transferring to him the power of language.

Yet she is "the small holding the heartbeat of the large", a phrase she uses to describe the cupola in which she waits day and night for Ahab's return. This phrase embodies the theme of the entire text: It explains the relationship between Ahab's lost limbs (both leg and penis) to his manhood, his wife and home to his selfhood, and Moby Dick to the ocean, the latter of which is only important to Ahab inasmuch as it will spread its legs and deliver him the former as "justice", just as Ahab's wife had done.

Therefore the text illuminates those things we perceive as small - a nineteenth century wife, a limb, a single whale within an endless ocean - as those things on which madness and reason hinge.