Sidney's conception of art: the finest art hides its art (sprezzatura) and appears to have an independent existence (like something natural). He "was one of the first to discover the paradox, however, that such fine art results only from the artist's complete dedication to, and immersion in, his artifact" (99). Sidney calls this quality "energia" or forcibleness.
This release of energy is shaped by the program of Art, Imitation (mimesis), and Exercise ("total engagement with all possible worlds, imaginary and real" (99). This engagement allows the artist to Invent, that is to make "discoveries and connections about the data of the world" that most people miss (99). (Note that invention is not creating something new.)
To make such connections, the artist needs to use "God-given reason or powers of observation and reflection" (100). Thus the function of the poet and the power of the poet's art are connected. The artist creates using reason--the divine spark present in the rational soul--because God Who created the poet is a divine artist. God is the "Maker of the maker" (100). Sidney thus gives a definition of how inspiration comes about.

Sidney's Defense of Poesy or Apology for Poetry is itself an example of high art because it is modeled on the teachings of Cicero, "the grand master in Renaissance education" (100). We can recall that Cicero's rhetoric also played an important role in the Middle Ages where schoolboys also learned and copied it. Sidney's essay would be recognized in both periods as a legal defense--a case presented in court. Even with, however, the highly structured divisions of Cicero's rhetoric, the art of the whole is "so graceful and complete that it tends to hide the very art of its creation. The Defence is not art simple because it is an oration; it is art because it is so well done" (100).

Cicero's De Rhetorica
His rhetoric is meant to be used to deal with particular legal cases, not arguments in general. Sidney's Defense of Poesy can be read as The Case for the Fine Arts.
Sidney uses Cicero's six parts of argument plus one optional one in outlining the case for art:
I. Exordium: Introduction (p 934). Sidney's use of a little narrative to lead into a defense (or case for) his avocation as poet.
II. Narratio: Outlines the subject matter and points to be covered
Definition from etymology of words for "poet." Note use of Roman, Greek, and even Biblical authorities. Relation of poetry to prophecy. To Psalms. Recall that Sidney is "answering" Puritans who invested all their faith in the Bible.
Also, man the poet becomes god-like in imitation of God the Divine artist. (Daedelaus as important).
III. Propositio: Presents the thesis statement (p. 937) Poesy Š "is an art of imitation, for so Aristotle termeth it in the word mimesis--that is to say, a representing, counterfeiting, or figuring forth--to speak metaphorically, a speaking picture--with this end, to teach and to delight" (Norton, 937).
IV. Divisio, (938) Argument is divided into parts or topics for discussion. Three kinds of poets: Divine poets or vates (OT and pagan); philosophers (moral, natural, astonomical, or historical); makers (heroic, lyric, tragic, comic, etc.--those who create images of virtues or vices with delightful teaching.
V. Confirmatio: Outline of the argument and gives proofs (939)
Goal of all earthly learning is virtuous action.
How philosophy presents itself as able to lead men by argument to virtue.
Historians argue that, more than philosophers, they give examples of virtue to follow.
For teaching models of virtue, the poet excels over the historian whose histories must show at times the triumph of evil.
For moving people to act virtuously, the poet excels over the philosopher by his artistry in enticing people to read his works.
Here follows examples of different types of poetry and the lessons each teaches.
VI. Refutatio: Rejection of opposing arguments (947)
1st: that poetry is not as fruitful as other branches of knowledge is already answered.
2Nd: That poetry is lies--Unlike the sciences that claim truth and fail at it, the poet affirms nothing. He does not say what is or is not but gives pictures of what should be.
3Rd and 4th (argument not shown in our text.) Poetry infects people with sinful desires; Plato kicked the poets out of the republic.
VII.Digressio: (not one of the seven parts, but an oblique recapitulation and summary 948). Sidney questions why the English are producing so few good poets and no good dramatists (Shakespeare had not begun his plays in the early 1580's when the Defense was written). He especially criticizes the lack of the three unities in Elizabethan drama. He does praise Chaucer's epic Troilus and Criseyde and a few contemporary pieces. Again he argues vs. Tragicomedy--the mixing of genres. He also complains that the love poetry lacks the energia of the Greek writers. Then he classifies meter and rhyme and says how amenable English is to various types.
VIII.Peratio: Conclusion A summary, a plea, and a curse.