Violin Sonata in G minor Bg.5, (Devil's Trill Sonata) by Giuseppe Tartini(1692-1770)

The Violin Sonata in G minor, Bg.5, also called Tartini's Dream or Devil's Trill Sonata(Italian: Il trillo del diavolo), is a solo violin sonata ​created by Giuseppe Tartini (8 April 1692 – 26 February 1770), an Italian Baroque composer and violinist. 

​According to the legend, Tartini was inspired to write the sonata by a dream in which the Devil had played.

Tartini allegedly told the French astronomer Jérôme Lalande that he had dreamed that the devil had appeared to him and had asked to be Tartini's servant and teacher. At the end of the music lesson, Tartini handed the devil his violin to test his skill, which the devil began to play with virtuosity; delivering an intense and magnificent performance. So singularly beautiful and executed with such superior taste and precision, that the composer felt his breath taken away.The complete story is told by Tartini himself in Lalande's Voyage d'un François en Italie:

One night, in the year 1713 I dreamed I had made a pact with the devil for my soul. Everything went as I wished: my new servant anticipated my every desire. Among other things, I gave him my violin to see if he could play. How great was my astonishment on hearing a sonata so wonderful and so beautiful, played with such great art and intelligence, as I had never even conceived in my boldest flights of fantasy. I felt enraptured, transported, enchanted: my breath failed me, and I awoke. I immediately grasped my violin in order to retain, in part at least, the impression of my dream. In vain! The music which I at this time composed is indeed the best that I ever wrote, and I still call it the "Devil's Trill", but the difference between it and that which so moved me is so great that I would have destroyed my instrument and have said farewell to music forever if it had been possible for me to live without the enjoyment it affords me.

Mesmerized by the devil’s brilliant and awe-inspiring playing, Tartini attempted to recreate what he had heard. However, despite having said that the sonata was his favorite, Tartini later wrote that it was "so inferior to what I had heard, that if I could have subsisted on other means, I would have broken my violin and abandoned music forever."

The sonata, written for violin with basso continuo (figured bass), is written in four movements:

1. Larghetto affettuoso
2. Allegro moderato
3. Andante
4. Allegro assai — Andante — Allegro assai
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The first movement, begins gently and reflectively, with languid double stops and a flowing violin melody line filled with tasteful embellishments. The melody, which moves from the tonic to the mediant key in the middle of the movement includes several deceptive cadences, before returning once again to a tonic theme similar to the beginning. A crisp, quick, highly decorated bravura follows, preceding a brief cantabile slow movement, said to signify Tartini's dream state.

The last movement, technically difficult, begins fast, before dissolving into repeated, modular violin melody over an intensifying accompaniment. This leads to a slow chromatic theme, followed by more sequences of the two themes. The source of the sonata's nickname is a passage where the violinist trills while simultaneously playing arpeggiated triads. The bravura cadenza that is frequently played was composed by Fritz Kreisler. The accompaniment joins the violin again for the last few dramatic measures. The trill in the last movement is one of the earliest examples of a trill illustrating a musical theme.

While Tartini claimed he composed the sonata in 1713, scholars think it was likely composed as late as the 1740s, due to its stylistic maturity. It was not published until 1798 or 1799, almost thirty years after the composer's death.

The sonata is Tartini's most famous composition. It is notable for its technically difficult passages that requires a number of technically demanding double stop trills and is difficult even by modern standards.

It would become the basis for Cesare Pugni's 1849 ballet ​Le Violon du diable, as well as Chopin's Prelude No. 27.​

Giuseppe Tartini sculpture in the Basilica of St Anthony in Padua

Giuseppe ​Tartini was born in Piran, a town on the peninsula of Istria, in the Republic of Venice (now in Slovenia).

It appears Tartini's parents intended him to become a Franciscan friar and, in this way, he received basic musical training. He studied law at the University of Padua, where he became skilled at fencing. After his father's death in 1710, he married Elisabetta Premazore, a favorite of the powerful Cardinal Giorgio Cornaro, who promptly charged Tartini with abduction. Tartini fled Padua to go to the monastery of St. Francis in Assisi, where he could escape prosecution. While there, Tartini took up playing the violin.

Legend says when Tartini heard Francesco Maria Veracini's playing in 1716, he was impressed by it and dissatisfied with his own skill. He fled to Ancona and locked himself away in a room to practise, according to Charles Burney, "in order to study the use of the bow in more tranquility, and with more convenience than at Venice, as he had a place assigned him in the opera orchestra of that city".

Tartini's skill improved tremendously and, in 1721, he was appointed Maestro di Cappella at the Basilica di Sant'Antonio in Padua.

Giuseppe Tartini was the first known owner of a violin made by Antonio Stradivari in 1715, which Tartini bestowed upon his student Salvini, who in turn gave it to the Polish composer and virtuoso violinist Karol Lipiński upon hearing him perform: the instrument is thus known as the Lipinski Stradivarius.