Alexander Porfirevich Borodin was a spare-time composer, but none-the-less a great composer for that.  He was born in St Peterburg of Russian noble blood, his father 62, his mother 25.  He showed aptitude and great love for music from a very early age,  but his mother insisted that he study medicine, not music.  He was not suited to medicine, so became a professor of chemistry at the St Petersburg Military Academy of Medicine. He was very successful and deeply involved with his academic and research responsibilities in the field of chemistry, but still found time to compose and perform music.

He became a member of the unofficial circle of the Russian "Five", in particular he was a friend of Mussorgsky and of Balakirev. (The others are Rimsky-Korsakov and CÚsar Cui).  Borodin found it easy to compose naturally flowing melodies, with enormous spontaneity.

He wrote 2 symphonies, the symphonic poem "In the Steppes of Central Asia", 3 string quartets, and the unfinished opera "Prince Igor". Rimsky-Korsakov completed Prince Igor after Borodin's death. The Polovtsian Dances are orchestral pieces from the ballet segment of the opera Prince Igor, and represent the most-often played work of Borodin at concerts today.  Also, one theme from this has been copied into a 20th century light opera "Kismet" and set to words "Stranger in Paradise". 

The theme from the 3rd movement of his 2nd String Quartet contains an often quoted unforgettable flowing melody.