Some reproductions of Wordsworth's poem "Ode to Duty" include the...
Epigraph: "I am no longer good through deliberate intent, but by long habit have reached a point where I am not only able to do right, but am unable to do anything but what is right" (Seneca, Letters 130.10).
Some reproductions of Wordsworth's poem "Ode to Duty" include the above epigraph, which helps develop the meaning of the poem's opening: "Stern Daughter of the Voice of God! / O Duty!" Duty is described by Wordsworth as the stern daughter of the voice of God because Wordsworth makes the dual points that (1) duty is control through reason (rational thought) and (2) duty is love itself.
Wordsworth refers to personified Duty as the stern Voice of God because he sees and wants to portray the dual nature of Duty as an explanation for why he is casting off unfettered freedom and unquestioning trust to embrace reason, confidence, guidance, and self-sacrifice. As Seneca reached a point in life wherein his ability to do right, to follow the law of right, became confident second nature, so Wordsworth pleads with personified Duty to "let [his] weakness have an end."
Wordsworth contrasts duty's stern law against his former way of blindly giving his trust as a result of his love of freedom (the antithesis of control).
I, loving freedom, and untried;
Yet being to myself a guide,
Too blindly have reposed my trust.
As Wordsworth sees duty, duty is stern, a lawgiver and law itself. Duty gives freedom; it is victorious, calming strife. Duty provides "guidance," counters "weakness," gives "confidence," and is "the light of truth." Duty is also God's most benevolent attribute: duty is love, spoken by the "Voice of God." Wordsworth pleads with Duty to change his weakness for a "spirit of self-sacrifice" and confidence attained through reason (rational thought).
To humbler functions, awful Power!
I call thee: I myself commend
Unto thy guidance from this hour;
Oh, let my weakness have an end!
Give unto me, made lowly wise,
The spirit of self-sacrifice;
The confidence of reason give;
And in the light of truth thy Bondman let me live!
To examine this analysis in more detail, Wordsworth connects duty to God's love in skillfully composed but diffused imagery (imagery hard to pin down to one allusion, metaphor, or description) through several scattered literary techniques. He employs an allusion to the "Voice of God," which is a voice of love; a personification to "saving arms," alluding to God's loving salvation; a personification as one that "dost wear / The Godhead's most benignant grace;" and the metaphor "love is an unerring light," which is a bridge to "[Duty] I now would serve more strictly."
Wordsworth paints this loving voice of God as a stern daughter because now, in wiser years, he sees Duty as the unerring light of "victory and law." He sees Duty as the power that sets "free" and as that which can "calm'st the weary strife of frail humanity." Duty is not passively loving, but giving of "firm support." Duty is a "Stern Lawgiver," and the "awful Power" that preserves "the stars from wrong."