I Modi was a fascinating book originally printed around 1524 and perhaps one of the earliest depictions of overtly erotic art in modern Europe. Several versions have been produced since the original was made. The original I Modi was a series of 16 highly accomplished engravings by Marcantonio Raimondi, based on drawings by Giulio Romano, student of Raphael, printed from copper plates showing different sexual positions.
There is a popular story that the prints of I Modi were actually based on a series of erotic paintings that Giulio Romano was doing as a commission for Federico II Gonzaga’s new Palazzo Te in Mantua. In another version of the story Romano (in a fit of rage over pay) made the drawings on the interior walls of the Vatican that he was supposed to be decorating. These story are definitely myths. According to recent research by Bette Talvacchia, Romano gave the drawings to Marcantonio Raimondi as a parting gift when Romano left Vienna to decorate the Palazzo Te in Mantua. Raimondi then made engravings of these drawings.
The first edition of I Modi was first published by Raimondi in 1524 in Vienna and it rapidly became popular. Unfortunately, it wasn't long before the Vatican found out about it and, deeming it to be obscene, demanded that all copies should be destroyed and Raimondi imprisoned. Romano did not receive any punishment, presumably because of his ties with the Vatican, though the official reason is because his erotic drawings were not meant for circulation within the public, whereas Raimondi's engravings obviously were.
In 1527, Aretino, poet and political satirist, campaigned for the release of Raimondi. I'm not sure how he achieved this since Aretino wasn't a popular figure with the Vatican, but sure enough Raimondi was released later that year.
According to a letter by Aretino, when Raimondi was released he wanted to see the drawings that had caused all this commotion. Upon seeing the original erotic drawings, Aretoni says he was filled with the same inspiration that had been felt by the original artist.
Aretino then wrote 16 erotic sonnets to accompany each of the drawings, describing the scene in each one, and I Modi was then reprinted with the 16 sonnets and engravings in 1527.
This edition proved to be even more popular than the first, spreading across Europe, which the scandal of the first edition no doubt encouraged. According to Renaissance period historian Vasari, copies of I Modi were found in the most unexpected places indicating the possession by the Vienna elite.
Sadly, every one of these copies were also destroyed by order of the Vatican.
Today, every known copy of the original I Modi has been destroyed, and all that remains is a series of nine fragments, carefully cut from the full engravings to censor anything explicit, which are currently in the British Museum, as well as two copies of Posture 1, one of which is suspected as being a forgery by Count de Waldeck.
Fortunately, we do know quite a bit about what the original I Modi looked like. In 1550 a counterfeit copy of I Modi came into circulation, however this copy was made from woodblock prints instead of engravings, and they were rather crude woodcuts as well and contained several literary errors in Aretino's sonnets.
Also, in the mid 1800's, Count de Waldeck released a series of drawings that he says were based on original tracings from I Modi.
There is also another series of erotic engravings from 1798 based on drawings by Agostino Carracci with sonnets by Aretino that for some reason Wikipedia strongly links with I Modi, though these engravings appear to be unrelated to the original edition.