Bach was born at Eisenach, Germany, the 11th son and youngest child of Johann Ambrosius Bach (1645--95) and Elisabeth Lémmerhirt, members of a remarkable musical family.
By the time he was 10, his parents had died, and he was brought up by his older brother Johann Christoph Bach (1671--1721), who was the organist at Ohrdruf and taught him the organ and clavier.
At 15 he won a place as a chorister at Michaelskirche, a boarding school for poor boys in Lüneburg, where his family were already appreciated.
His musical experience thus far had developed from the string-playing tradition of his immediate family to composing and performing keyboard and sacred music. From 1703--7 he was organist at Neukirche Arnstadt, where he had keenly followed the building of the new organ. However, he began to neglect his duties as choirmaster, preferring to immerse himself in keyboard music.
He also angered the authorities with his innovative chorale accompaniments, and by his failure to produce cantatas. To make matters worse, after two years service at Arnstadt, in October 1705 when he was 19, he walked 230 miles to hear Dietrich Buxtehude, the Danish composer and organ player at St Mary´s church in Lübeck, and returned to his post three months later than expected, in January 1706.
In June 1707 he left Arnstadt and became organist at St Blasius, Mülhausen, where the pastor was a strict priest who objected to any but the simplest music in church. That October he married his cousin Maria Barbara Bach (1684--1720).
Bach transferred to the ducal court at Weimar as Konzertmeister in 1708 and, after being passed over for the job of Kapellmeister there, became Kapellmeister to Prince Leopold of Anhalt-Cöthen in 1717, in whose service he became known as an outstanding organist. The prince was a Calvinist, so music played only a small part in his worship, and Bach was at liberty to compose and perform many secular works. He gave recitals, and wrote the Toccata and Fugue in D Minor, the Fantasia and Fugue in G Minor, the Prelude and Fugue in C, as well as other instrumental music, including the Brandenburg Concertos (1721), and the first book of Das wohltemperiete Klavier (1722, The Well-Tempered Clavier).
Widowed suddenly in 1720, and left with four children (he had six by Maria, but only four survived), in 1721 he married Anna Magdalena Wilcken (1701--60), an accomplished singer, harpsichordist, and copyist, for whom he wrote a collection of keyboard pieces. Of their 13 children, six survived, and for them he wrote his Clavierbüchlein (1720, Little Book for the Keyboard). Six sonatas for the solo violin, also written then, were forgotten and not found until the next century.
A devout Lutheran, Bach´s desire to get back into church music became strong and, after much deliberation, he accepted a lower position as cantor of the Thomasschule in Leipzig in 1723, where he remained for the rest of his life, despite disagreements with his colleagues and the authorities. In an attempt to strengthen his position there, he solicited the title of Court Composer to the Elector of Saxony, presenting the Goldberg Variations (1722), a harpsichord work named after one of his pupils.
But his main task at Leipzig was to supply cantatas for the city churches each Sunday, and he wrote about 300 of these, of which 200 remain. He composed much of his best work in this period, including the St Matthew Passion (1727 and/or 1729). From 1729--1741 he was also director of the Collegium Musicum (the local music society), giving weekly concerts, and his family home became a centre of musical pilgrimage. Many eminent musicians, who included several relations, became his pupils.
A visit in 1747 to his son Carl Philip Emmanuel, who was court harpsichordist, resulted in an invitation from Frederick the Great of Prussia to try his latest Silbermann pianofortes and improvise a fugue. As a result Bach subsequently offered the king his collection, Das musikalisches Opfer (1747, Musical Offering), which included a trio for flute, violin, and clavier. At about the same time (1748--9) he completed the full Mass in B Minor, which he never performed.
A conscientious copyist, his eyes had long been failing him, and despite an operation he became almost totally blind. He died of a stroke at Leipzig while engaged on a series of fugues for the keyboard - the monumental work The Art of the Fugue.
