The first sonnets were written by Jacopo da Lentino (a Sicilian lawyer at the court of Fredrick II) in 1230 or 1240. The sonnets written in the following century by Cavalcanti, Dante and Petrarch established the Italian form.
The Italian sonnet as Petrarch used it, consisted of fourteen hendecasyllabic lines. The first eight lines were nearly always arranged in two enclosed quatrains rhyming abba abba: this kind of rhyme is called “closed” or “enclosed”.
In the remaining six lines two or sometimes three new rhymes were introduced. These rhymes were variously arranged, but most commonly so as to produce two symmetrical tercets rhyming ccd ccd, or cde cde. By general consent, arrangements which would close the sonnet with rhymed couplet were avoided by most sonneteers.
The Italian sonnet had a logical basis. The first quatrain stated a proposition; the second proved it; the first tercet confirmed it and the second tercet drew a conclusion.
Between the octave and the sestet there was a “turning point” or “volta”. The purpose of volta was to develop the subject of the sonnet to its conclusion.
The sonnet was introduced into England by sir Thomas Wyatt. Wyatt came from a Yorkshire family and was educated at St. John’s College Cambridge. He held various diplomatic posts in the service of King Henry VIII in Spain, France, Italy and the Netherlands. His first visit to Italy in 1527 stimulated him to translate and imitate Petrarch’s sonnets.
For his adaptations and imitations of Petrarch’s sonnets he copied the Italian form, except that he always arranged the rhymes of his sestet to end with a couplet.
The final couplet was the only feature of Wyatt’s rhyme scheme that his younger contemporary and follower, Henry Howard, Earl of Surrey, took over. Surrey wrote his sonnets with the first twelve lines rhyming in three separate quatrains (abab cdcd efef). The form introduced by Surrey became the most popular with the Elizabethans.
Wyatt ’s form is known by the name of his master (Petrarch), the Petrarchan form. Surrey’s form is known by the name of its greatest practitioner ( Shakespeare), the Shakespearean form. This is also called the Elizabethan form. In the Elizabethan or Shakespearean sonnet there can be variations as far as the rhyming scheme is concerned.
The rhyming scheme can be enclosed (abba cddc effe gg) or interlaced ( abab cdcd efef gg).
Sometimes an impression of separation into an octave and a sestet is given by a limitation to two rhyme-sounds in the octave (abab abab cdcd ee).
Surrey also played an important part in the introduction of the sonnet into England. Another important invention due to him is blank verse (unrhymed iambic pentameter : a line composed of five feet or ten syllables). Surrey’s and Wyatt’s works, together with some poems by unknown authors, were published in a book called Tottel ’s Miscellany, from the name of its printer (Richard Tottel). Tottel ’s Miscellany is the only collection of sonnets printed before the great revival of the sonnet in 1580.
 to establish = rendere ufficiale
 variously arranged = disposte in modo vario
 most commonly = più comunemente
 by general consent = di comune accordo
 rhymed couplet = distico a rima baciata
 to avoid = eliminare
 The first quatrain stated a proposition = La prima quartina affermava una proposizione
 sestet = sestina
 purpose = scopo
 to develop = sviluppare
 the subject = il tema
 to its conclusion = verso la sua conclusione
 diplomatic posts = incarichi diplomatici
disposte le rime della sua sestina per terminare con un distico
 per quanto riguarda lo schema delle rime interessato
 dovuta a lui