Fernando Sor (1778 - 1839) was a Spanish guitarist and composer, born in Barcelona. In Spain he is sometimes known as the "Beethoven of the Guitar". The guitar part is originally a study by Sor for guitar solo. The melody (ad lib.) is written by D. Fortea.
Watch a performance of this arrangement on YouTube by the duo TenStrings.
Sor like you've not heard before...played here by Ten Strings.