Discuss the theme of unrequited love.

Some scholars read "Song: To Celia," also known as "Drink to Me Only," as an anti-idealization poem written tongue-in-cheek by Jonson. That is to say, it is thought that Jonson is ridiculing the Petrarchan love and poetic conventions so popular during and so in keeping with the Renaissance, a time when philosophy regarding the aim of poetry held that inspired poetry was meant to reveal divine truth. While there is no apparent evidence for this anti-idealization position in either the tone of the poetic speaker or the mood of the poem--which ring as true poetic sentiment throughout--the position is supported by claims of Jonson's personal "antipathy" toward love poem conventions. For illustration, these love poem conventions are well represented in Edmund Spenser's famous sonnet cycle Amoretti.
SONNET. VIII.
MORE then most faire, full of the liuing fire Kindled aboue vnto the maker neere: no eies buy ioyes, in which al powers conspire, that to the world naught else be counted deare. Thrugh your bright beams doth not [the] blinded guest, shoot out his darts to base affections wound; but Angels come to lead fraile mindes to rest in chast desires on heauenly beauty bound. You frame my thoughts and fashion me within, you stop my toung, and teach my hart to speake, you calme the storme that passion did begin, strong thrugh your cause, but by your vertue weak. Dark is the world, where your light shined neuer; well is he borne that may behold you euer. (Amoretti, Edmund Spenser)
This approach to analysis of "To Celia" is founded in Historical Criticism and based on author biography, and it may well be a viable approach. On the other hand, for readers looking only at the text and taking an analytical approach that is founded on Formalism or New Criticism, both of which place the text above the author's biography, this tongue-in-cheek reading won't ring true. If Historical Criticism's author-focused approach yields a theme of rejected idealization of poetic and love conventions, such as stem from courtly love and Petrarchan sonnets, then an approach based on the text, as would result from Formalism or New Criticism, yields a theme of unrequited love, such as Spenser experienced while courting Elizabeth Boyle, as he recorded in Amoretti.
SONNET. X.
UNRIGHTEOUS Lord of loue what law is this, That me thou makest thus tormented be: the whiles she lordeth in licentious blisse of her freewill, scorning both thee and me. See how the Tyrannesse doth ioy to see the huge massacres which her eyes do make: and humbled harts brings captiues vnto thee, that thou of them mayst mightie vengeance take. But her proud hart doe thou a little shake, and that high look, with which she doth comptroll all this worlds pride bow to a baser make, and al her faults in thy black booke enroll. That I may laugh at her in equall sort, as she doth laugh at me & makes my pain her sport. (Amoretti, Edmund Spenser)
Looking at the text, and not taking into account Jonson's described disdain for hyperbolic conventions of love and poetry, the theme of unrequited love is apparent in the poetic tone, mood, narrative, and in the elevated status the poetic speaker gives to his desired love object.
ELEVATED STATUS
It is not at all evident that the speaker is positioning the lady as a goddess; it is not evident that he is positioning her above the status of the god Jove. It is clearly evident, though, that he is saying that he prefers her elixir of love ("leave a kiss but in the cup") to the nectar of the immortal god Jove.
Lines 7 and 8 pose a difficult passage. It is difficult because syntactical conventions have changed, although the syntax Jonson uses remains in the cannon of rhetoric as the following devices:

hyperbaton: rearrangement of normal word order, "Jove's nectar [Object] sup [Verb]"

ellipsis: omitting a word found in the previous clause, "Jove's nectar ... [ex]change [Jove's/that] for thine",

antithesis: contrary ideas that are opposites or represent contrasting degrees and that are expressed in a balanced sentence, PARAPHRASE: I could have Jove's nectar; but I will take your love.
The keys to understanding these controversial two lines are the word "But" and the word undergoing ellipsis, which is the implied possessive "Jove's nectar."
The syntax of line 7 begins with "But," the conjunction indicating contrary conditions. "But," indicates that the first statement is rejected in favor of the second statement: But might I have X, I would keep Y.
The syntax of line 7 splits the Verb "might sup" and locates the Subject and Object between the verbal elements: "might [Aux Verb] I [Sub] of Jove’s nectar [Obj] sup [Verb]. This relocation of Object and Main Verb is rhetorical hyperbaton. Normal English order is Subject, Verb, Object. Here, the order is Aux Verb, Subject, Object, Verb.
The syntax of line 8 is complicated because of Jonson's use of aphaeresis, which is the omission of a syllable at the beginning of a word. This in effect creates a new word. Using aphaeresis, Jonson drops "ex-" from the beginning of "exchange" leaving only "change." Thus the meaning to be understood by "change" is that of "exchange."
Syntactically, Jonson uses ellipsis to omit the Direct Object from the line 8 clause: "I would not change for thine."
A direct object answers What? or Whom? applicable to a verb: He gave What? She took Whom?
An indirect object, on the other hand, answers For whom? For what? or To whom?: They did it for her. They spoke for charity. Art was given to her.
Except in the case of instances of rhetorical ellipsis, English requires the presence of a Direct Object before there can be an Indirect Object: What? or Whom? must be answered before for whom? for what? or to whom? can be introduced.
You see that line 8 omits, because of the use of ellipsis, the Direct Object and goes from the Verb to the Indirect Object: "I [Sub] would not change [Verb] ___ [D.O.] for thine [I.O.]." The question is: "Change" what "for thine"?
Ellipsis may only be employed when the omitted word or phrase is present in the preceding clause. The omitted Direct Object of line 8 must be stated in line 7. The Object of line 7 is "Jove's nectar." The omitted D.O. of line 8 therefore must of necessity be "Jove's nectar." Line 8 must be understood as: I would not [ex]change Jove's nectar for thine ("But might I of Jove's nectar sup / I would not change [Jove's nectar] for thine."). In other words: Given a chance to have Jove's nectar, I would keep yours.
As a result of this analysis of vocabulary, of "But," and of the syntax of lines 7 and 8, we see that, while the speaker elevates the lady above Jove (I would take yours, not his), he does not make his lady higher than or even as high as Jove. Thus he does not equate his lady with or elevate his lady to the level of goddess: She is and remains mortal.
Remember that the "but" tells us that lines 7 and 8 present contrary ideas: the first idea will be rejected and the second, contrary one, accepted. The idea of Jove's superiority is rejected, and the idea of his mortal lady's worth is accepted:
PARAPHRASE: Even though you do NOT have the immortal nectar of gods, I choose you, mortal though you are.
The speaker elevates his lady above Jove, but he elevates her for the fact of her mortality. This presents an irony and a paradox because, ironically, he, like Odysseus, prefers his mortal beloved to immortal power, and, paradoxically, his soul's thirst, which needs a divine drink to quench it, is a thirst for she who is mortal though divine (a paradoxical condition), namely, his mortal beloved.

The thirst that from the soul doth rise Doth ask a drink divine;

NARRATIVE OF POETIC DISCOURSE
The narrative of the poem tells a story of unrequited love, love that is felt by one but unreturned by the other, as also expressed in Spenser's Sonnet XVIII:

So doe I weepe, and wayle, and pleade in vaine, whiles she as steele and flint doth still remayne.

The story starts with an event conveyed out of sequence in the second stanza. This event inspired the words of the first stanza. He sent her a fragrant wreath made of roses. She immediately returned them to him, after looking at them only long enough for her breath to fall on them. She utterly rejects his love suit. Yet, he in his amorous state, receives the roses again as a blessing that continues to grow, bloom, and emit fragrance solely because she breathed on the the roses.
The poem, which is intended as a song, is composed to explain to her his loving reaction to her rejection of the roses and to offer her a subtle, modest way to give him permission to swear his love to her:
PARAPHRASE: Drink to me with thine eyes, or leave a kiss in the cup, and I'll pledge my eternal love to you.
The fact that he needs to request this of her is proof in itself that his love--so far--is unrequited.
POETIC TONE AND MOOD
Tone
Tone is set by diction (high or low language), vocabulary, irony, sarcasm, and satire. Tone illuminates the poetic persona's (or prose narrator's) attitude toward what is being written about. As a result, tone can range from sincere to bitter, from loving to disapproving, from humorous to outraged, and many others in between. To determine the tone of the poetic speaker of "To Celia," we'll examine the components of tone.
Diction: High poetic diction is used. Figurative language, like metaphor and simile, is profuse. Rhetorical devices, like hyperbaton (rearrange syntax order), are profuse. High diction lends itself to a sincere tone.
Vocabulary: Vocabulary words are picturesque, painting beautiful images, and they are elegant, employing words that are not the simplest choices: pledge, drink divine, nectar, rosy wreath, honouring, withered, thereon. Elegant vocabulary lends itself to a sincere and earnest tone.
Irony: Irony is the statement or presence of the opposite of what is expected. For instance, if the speaker had said that, his beloved having breathed on the roses, they now withered at twice the speed and died, that would be the opposite of the expectation from a man pleading or a lady's love. This would be bitterly ironic.
Irony is present in lines 7 and 8 when the speaker chooses the lady's mortality and love above Jove's immortality. There is irony present in the second stanza when the rejected roses are perceived as growing and being fragrant because of mere contact with the lady. Irony that elevates the subject of the poem (speech) is an irony that establishes a sincere, admiring tone.
Sarcasm: Sarcasm is an ironic statement that is intended to hurt the listener's feelings. There is no accidental offense given with sarcasm; the hurt is intended and purposeful. There is no instance of hurtful remarks, thus no sarcasm. The tone is sincere.
Satire: Satire is the use of humor, ridicule, or irony to expose a person's (or society's) failings, flaws, or faults and to induce remorse leading to changes in behavior (or social norms).
While the speaker does mention what might be her failing (returning the roses), no flaws, faults, or failings are subjected to ridicule, humor or irony for the purpose of inciting remorse and changed living (although of course he hopes for her love, although won through kindly, poetic means producing beauty).
Combining all these components, the tone of the poetic speaker, in light of the above analysis, must be seen as sincere and genuinely earnest.
Mood
Mood is the emotional atmosphere of the narrative itself. This is different from the tone of the narrator. For instance, the tone might be somber because the narrator knows the ending of a story, although the story itself may start out as cheerful and light. While diction enters into creating mood, description, setting, and characterization are the chief components of mood.
Description: The descriptions of concepts provided by the speaker are beautifully picturesque signifying a mood of hope and bright expectation: "The thirst that from the soul doth rise / Doth ask a drink divine;...."
Setting: No setting is actually given, but we can imagine a few possible scenes: at a banquet across a table; at a party speaking face to face; at a party or banquet, he singing to her across a distance. Each of these possible settings is romantic, full of colors, sights, sounds, aromas. Each setting is a place where couples are flirting, conversing, arranging future trysts. Here in the setting is embedded a mood of bright promise, hope in love triumphant, love won.
Characterization: Characterization is how the characters in a narrative are presented: Are they good? Kind? Cruel? Vengeful? Foolish? Intelligent? Trustworthy? Dolts? While 16 lines is not very much for characterization, one of the beauties of Jonson's poem is that mental images of the speaker and the lady are called up before readers' eyes. He, using elegant diction and beautiful poetic devices and having an energetic tone, is seen as an admirable young man of talent and good will. She, though rejecting her suitor's love, is seen as beautiful, young, sweet, along with self-confident and determined. These characterizations add to the mood cheer, earnestness, and caring tenderness.
THEME
When all these elements are combined and viewed as a whole, the proposed theme of the rejection of idealization of love and poetic conventions falls flat: Nothing in the text supports this theme according to detailed analysis. What analysis does support is the theme of unrequited love, although, after analyzing mood (especially as created by characterization), tone and diction, a new optimism of bright hope and promise enters as a corollary of the theme of unrequited love: We hope, as the speaker hopes, that he will be successful in his love quest.