When it comes to musical dynasties, it's tough to top the Bach family. From town fiddlers to court composers, the Bachs dominated German music for seven generations. Today, Johann Sebastian towers above all his relatives, but there's another important Bach we shouldn't forget — especially today, on the 300th anniversary of his birth.

Carl Philipp Emanuel Bach, C.P.E. for short, was the second surviving son of Johann Sebastian, whose sturdy, impeccably built music made a great impression on the young composer.

Still, C.P.E. seemed to chafe against the old Baroque restraints by forging an innovative and dramatic new sound, especially in his keyboard music and symphonies.

So where did C.P.E. get all his radical ideas? Not from his father. Although Johann Sebastian personally gave his son a complete music education — and moral support — Harvard professor and Bach scholar Christoph Wolff says C.P.E. had a mind of his own.

"I think he became fascinated by modern trends," Wolff says. "His father actually supported that, and that was, I think, part of his educational concept not to make clones. And C.P.E. Bach became his very own character."

One of the modern trends C.P.E. helped design — while he was bored with his 27-year job as harpsichordist to Frederick the Great in Berlin — was something the Germans called empfindsamer Stil. The literal translation is "sentimental style."

But it's not about being delicate, Wolff says. It's more about plugging raw emotions into music by pivoting from one mood and dynamic shade to another. "With staccato and slurred phrases, small motifs are pitted against each other," Wolff explains. "And that is something completely new in the compositional style of the mid-18th century and had a huge impact on European music."

Pianist Danny Driver, who has recorded two albums of keyboard sonatas by C.P.E., says the music have felt like a roller coaster to people listening at the time.

"The most striking thing about it is the very quick change of character and the very quick change of harmony," Driver says. "It's like a stream of consciousness internal dialogue in a way."

While listening to C.P.E.'s F-sharp minor sonata, Driver noted some of the composer's quirky characteristics:

"Well, here you've got this rather manic, energetic fantasia-like passage that suddenly, abruptly stops. And then, a lovely aria melody comes in, like a singer with a light accompaniment. And because the juxtaposition happens so quickly we're left guessing as to what comes next. Are we going to carry on in this sort of vein? And again, the way the harmony suddenly changes, he just changes a single note in a chord that completely turns the emotional effect upside down."

Hans-Christoph Rademann, who's just released an album of C.P.E.'s sacred choral music, says that Bach's restless, radical new style fits within history — with the upheaval of the Seven Years' War, the shifting of nations and the Enlightenment, which encouraged individualism.

"I think it was a question of this time," Rademann says. "The time was also a time of change and new ideas. And this music, it was a new feeling, a very good feeling."

Writing a dull piece of music didn't seem to be part of C.P.E.'s playbook, even if he did fall into that peculiar crack between the old-fashioned Baroque period of his father and the newfangled freedom of the Classical era, which would star Haydn and Mozart.

In his double concerto, C.P.E. actually bridges that gap. It's for harpsichord — old school — and fortepiano, the keyboard of the future. Driver, who performed the concerto recently in London, says the two instruments chase each other's tails.

"It's literally, from the very first movement, one bar piano, one bar harpsichord, a little bit of orchestra, then something else. The exchange of ideas is so quick," he says.

The music is old but Driver insists it's relevant: "It's not postmodern, but it almost feels postmodern in the sense that there's this sort of collation of different ideas and different feelings all sort of rolled into one. I think it's of today as it was of its time."

And who would have thought that all those weird juxtapositions and breakneck mood swings in the music of Johann Sebastian Bach's son C.P.E. would end up, some three centuries later, making a surprisingly apt soundtrack for our fractured, multi-tasked, 21st-century lives.

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C.P.E. Suggested Listening

Concerto for Harpsichord and Fortepiano in E-flat major – 'Presto' (Wq 47)

"Double Concerto for harpsichord, fortepiano, 2 flutes, 2 horns, 2 violins, violetta & continuo in E flat major, H. 479, Wq. 47 [3. Presto]"

Here C.P.E. Bach bridges the gap between the two musical eras we now call Baroque and Classical, by writing an infectious concerto for harpsichord and the then-new fortepiano, the keyboard of the future.

Symphony in B minor – 'Presto' (Wq 182)

"Sei sinfonie, symphonies (6) for strings & continuo ("Hamburg"), H. 657-662, Wq. 182 [Symphony No. 5 in B minor: 3. Presto]"

The symphony as we know it today was in its infancy during C.P.E.'s time, but he helped forge the dramatic elements that Haydn and Mozart would exploit as they further developed the genre. The jarring dissonances and whiplash rhythms in this must have blown more than a little powder out of the wigs of its listeners.

Keyboard Sonata in G minor – 'Allegro assai' (Wq65/17)

"Sonata for keyboard in G minor, H. 47, Wq. 65/17 [Allegro assai]"

Danny Driver, the pianist on this excellent album, loves the quirky, restless tone of many of C.P.E. Bach's keyboard sonatas. The very quick changes of character and harmony, he says, create "a stream of consciousness internal dialog."

Heilig ist Gott – 'Chorus of the Angel and the People' (Wq217)

"Helig (Te Deum Laudamus), for voice, double chorus, 2 oboes, bassoon, 3 trumpets, strings & continuo, H. 778, Wq. 217 [2. Chor der Engel und Völker. Heilig, heilig, heilig ist Gott]"

After C.P.E. Bach left the employ of Frederick the Great in Berlin, he moved to Hamburg to direct all of the church music in the city. His Heilig ist Gott, published in 1779 and remarkable for its dramatic effects, was considered one of the greatest pieces of German sacred music at the time.

Keyboard Sonata in C major – 'Poco allegro' (Wq 48/5)

"Sonata for keyboard in C major (Prussian Sonata No. 5), H.28, Wq. 48/5 [No. 1, Poco allegro]"

Here's a chance to hear C.P.E. Bach's keyboard music on his preferred keyboard instrument, the clavichord, on which he was known to improvise for hours on end. Its pressure-sensitive keyboard provided the composer with pathways for experimentation in pivoting from very quiet to very loud within the same measure.