Sidney's critical treatise was written about 1580 but not published until 1595, after his death, when two
seperate editions were published under different titles, An Apology for Poetry and The Defence of Poesy.
It is said that he wrote the Apology in response to a work which had been dedicated to him, attacking poetry and plays; the author of this book, Stephen Gosson(1554-1624), was supposedly misled by Sidney's staunchly Protestant and anti-Catholic political associations into believing that he would be sympathetic to Puritan-style attacks on poetry as a frivolous and dangerous miscalculated.
'Poesy', says Sidney, 'is an art of imitation, for so Aristotle termeth it his word mimesis, that is to say, a representing, counterfeiting, or figuring forth; to speak metaphorically, a speaking picture, with this end, to teach and delight.' (The latter formula, of course, derives from Horace rather than Aristotle.) But poetry does not offer a literal description of reality(which is why it does not tell lies, as some claim; it does not assert untruths as truths); it offers rather a heightened version of reality; 'Nature never set forth the earth in so rich tapestry as divers poets have done; neither with pleasent rivers, fruitful trees, sweet smelling flowers, nor whatsoever else may make the too-much-loved earth more lovely; her world is brazen, the poets deliver only a golden.'
Sidney contrives to answer all those who scorn or hate poetry, including Plato, who, he argues, 'only meant to drive out those wrong opinions of the Deity, (whereof now, without further law, Christinaity hath taken away all the hurtful belief)... So as Plato, banishing the abuse, not the thing... shall be our patron and not our adversary.
In the drama, he objects 'how all their plays be neither right tragedies nor right comedies, mingling kings and clowns, not because the matter so carrieth it, but thrust in the clown by the head and shoulders to play a part in majestical matters, with neither decency nor discretion'; he admires the 'stately speeches and well-sounding phrases' of Sackville and Norton's1 early tragedy, Gorboduc(acted 1561;first published 1565), 'full of notable morality', but even that is censured 'for it is faulty both in place and time' - breaking what he believes to be Aristotle's precepts on the unities. Sidney is, in short, a conservative in the Horatian manner, believing in decorum and a proper respect for ancient examples which have stood the test of time. But he is not totally dogmatic.
Sidney writes as a man of the world (he mentions his diplomatic missions, for example), for whom poetry has a natural and honoured place in his life. The Arcadia2 and Astrophel and Stella3 he writes as though his readers will be conversant with poetry and may well also write themselves. This mode of criticism - poets writing as if for potential fellow - poets - survived well into the eighteenth century; the idea that creative artists are likely to be the most knowledgeable critics is not dead ever now. The concept that literary criticism may be a fit pursuit for a gentleman, that it should remain a casual, amateur occupation, is peculiarly English and is still reflected in the English reticence about modern American and European critica; approaches which are avowedly specialist and 'professional'.