Reason versus Love
Throughout the sequence, Astrophel struggles between his love for Stella and his rationality. Because Stella is married, Astrophel recognizes that he can never have a full relationship with her. Moreover, he recognizes that his infatuation with her is foolish and irrational. He isolates his friends and family, damages his reputation at court, and threatens his emotional and mental wellbeing through his obsession with Stella. Yet, even as his reason urges him to give up Stella for his own good, Astrophel cannot stop loving her. The sonnets are full of dialogues between Reason and Love in which Astrophel admits that Reason is correct, but he remains unable to give up his love. Even at the end of the sequence, Astrophel's love prevails over his reason; he is happier having loved her and lost her than never having loved her at all.
Petrarch
The love poetry of Petrarch is a primary theme running throughout the sequence. Petrarch's love and description of Laura in the 366 poems Il Canzoniere are closely mirrored in Astrophel's love and description of Stella. Petrarch's preoccupation with Laura causes his overwhelming joy as well as tormenting desires, the same conflict that Astrophel experiences for Stella. Sidney also uses the rhyme scheme used by Petrarch in his poetry, abba abba cdc ece. But Sidney also bends Petrarch's rhyme scheme, incorporating fifteen variants at different points in the sonnet sequence. Sidney also mirrors Petrarch on a more general level. His use of an ongoing narrative, conflicts between love and desire and between love and reason, and discussion of poetic creativity are all characteristic of Petrarch's works. Above all, Sidney is recognized as the poet who introduced the key features of Italian love poetry to England and, in so doing, single-handedly changed the course of English Renaissance literature.
Love versus Desire
Astrophel's inability to limit his desire for Stella ultimately destroys their relationship. Because of her marriage, Stella is unable and unwilling to enter a physical relationship with Astrophel. Although she loves him, she insists that their love remain completely platonic. Astrophel is unable to accept this condition and limit his emotions for Stella to a chaste and pure love. (Compare the medieval story of Abelard and Heloise.) Despite his best attempts, his desire continues to get the better of him until he kisses Stella, a kiss that is the beginning of the end of their romance. Astrophel's inability to contain his desire expresses his contemporary understanding of male and female sexuality. Women were expected to be chaste and pure, without the ability or drive for sexual desire. Men, for their part, were thought to be extremely potent and almost bestial in their desire. With this in mind, Astrophel's desire for Stella can be recognized as a natural state of wanting, one which he truly cannot control. At the same time, however, Stella is unwilling to accept Astrophel's desire as an uncontrollable force, so she insists that he become as pure and chaste as she is.
The Sun
Stella is described as the sun in numerous sonnets in the sequence. Through this interpretation, Astrophel reiterates Stella's position in the celestial plane, but closer to home than the millions of stars (as her name suggests). Stella is the center of the universe and the sole source of light in Astrophel's life. Stella is also tied to classical mythology through this representation; in the sequence, Astrophel frequently invokes Phoebus, or Apollo, the god of the sun and music. As the sun, Stella represents things that are light, good, and virtuous in the world. Just as the earth is thrown into cold and darkness without the sun, Astrophel cannot survive without Stella.
Day versus Night
Because Stella is described as the sun, Astrophel connects his perception of day and night to her presence or absence. When Stella rejects him for the first time and the lovers are separated, Astrophel experiences the darkness of a world without his personal "sun." Before Stella's confession of love, Astrophel preferred the night because it allowed him to escape reality. It was the only time that he could dream of Stella and see her as he desired her: beautiful, brilliant, and his lover. After Stella's rejection, the night is no longer a haven for Astrophel's imagination. At the same time, his nights are still better than his days because the night never had the sun in the first place.
Wit
In the 108 sonnets of the sequence, Sidney uses forms of the word "wit" forty-two times. Historically, the term wit (or witan in Old English) meant "to know." In Philip Sidney's time, wit referred to mental ability and intelligence. In this case, wit meant an author's capacity for literary invention, which is Astrophel's primary poetic goal in composing his sonnets for Stella.
Poetic Ability
The entire sequence is an allegory that shows off Sidney's abilities. Sidney is represented by Astrophel; Penelope, by Stella. While the character Astrophel protests sometimes that he is not up to the poetic tasks, he does so with poetic power. He also writes his sonnets with disdain for poets who cannot be creative with the poetic tradition. Sidney goes so far as to be creative even with the sonnet's rhyme scheme.
