ed by an incident
which marked the latter period of his busy life. His third son, Carl
Philip Emanuel, had entered the service of Frederick the Great, and
was acting as cembalist in the royal orchestra. His Majesty, who was
exceedingly fond of music, and a considerable player on the flute, had
repeatedly expressed a wish to see Bach, and from time to time sent
messages to this effect to the old composer through the latter's son.
Bach, however, intent upon his work, for a long time ignored these
intimations of royal favour, until at length, in 1747, Carl brought to
him an imperative demand from his royal master which Bach saw that he
could not disobey without incurring the King's displeasure.
Accordingly, he set out for Potsdam with his son Friedemann. The King
was about to begin his evening music when a servant brought to him a
list of the strangers who had arrived at the castle that day.
Frederick glanced at the paper, and then turned to his musicians with
a smile. 'Gentlemen,' said he, 'old Bach has come!' and down went his
flute. Bach was immediately sent for--he had not time even to change
his travelling-dress--and with many excuses he presented himself to
the King. His Majesty received him with marked kindness and respect,
and when the courtiers smiled at the old musician's embarrassment and
his somewhat flowery speeches, Frederick frowned his disapproval. He
then conducted Bach through the palace, showing him the various points
of interest, and insisted on his trying his Silbermann pianofortes, of
which he had quite a collection. Bach extemporised on each of the
instruments, and then Frederick gave him a theme which he reproduced
as a fantasia, to the astonishment of all present. The King next
requested him to play a six-part fugue, and Bach extemporised one on a
theme selected by himself. The King, who stood behind the composer's
chair, clapped his hands with delight, and exclaimed repeatedly, 'Only
one Bach! Only one Bach!' It was a visit replete with honours for the
old master, and when he returned home he expressed his gratitude by
writing down and elaborating the piece which he had composed on the
King's theme, dedicating it to His Majesty under the title of
'Musikalisches Opfer' (Musical Offering), and sending it to Potsdam
with a letter begging its acceptance.

Late in life, and just after he had completed his great work, 'The Art
of Fugue,' Bach became totally blind--the result, no doubt, of the
heavy str