Given the fact that in the sixteenth century, when Sidney lived and composed his poetry, it was only really the upper classes, some of the aspiring middle classes, and a select few other professions that could actually read, it is clear that the audience of Sidney's poetry was upper class. Illiteracy was rife and so this meant any published work at the time was only meant for a narrow spectrum of society. As for the political issues that Sidney tackled, he makes little reference to such issues in his work, however he was a known defender of the Protestant cause, and this was something that was greatly advanced when he spent some time in Europe and met with various Protestant leaders in places such as France and Holland. This particularly was heightened after the Massacre of Saint Bartholemew in 1572, when a large number of protestants were brutally killed in cold blood in France.
In terms of the issues that can be identified in his work, however, it is clear that his Defence of Poesie is a major work of criticism in literature, and such was its impact that it is still studied today. In addition, his sonnet sequence entitled Astophil and Stella is rightfully seen as rivalling the sonnets of Shakespeare in the way that it charts Sidney's own unhappy relationship with Penelope Rich, whom he was unable to marry. Note for example this famous quote from one of his sonnets, where the speaker writes of how he found inspiration to describe his love for Stella:
Thus, with child to speak, and helpless in my throes,
Biting my truant pen, beating myself for spite:
Fool! said my muse to me, look in thy heart, and write.
No political issues are discussed in such works, but his description of the frustrations and joys of being in love when that love is doomed to be thwarted makes compelling reading, and are excellent examples of the Petrarchan sonnet form. His contribution to English literature is shown through the way that he is credited with being part of a group of poets who helped create the conditions for the birth of the English Renaissance.