The organ and its long history provide proof that humanity will devote great resources and ingenuity toward the quest for music.

The instrument dates back to ancient times, and its basic technology survived through the Dark Ages, when so much else of ancient engineering was forgotten. The organ reached an exalted stage during the baroque era. Indeed, baroque organs have been described as landmarks in technology – perhaps the most complex mechanical devices to exist before the Industrial Revolution.

An organ produces sound when pressurized air is pushed through tubes or pipes as they are selected using a keyboard. Its origins have been traced to the hydraulis, thought to have been invented by a Greek engineer in the third century B.C.E. The ancient mechanism relied on hydraulics – the use of water pressure – to compress the air. The Greco-Roman hydraulis seems to have been built for entertainment in large public places – somewhat analogous, perhaps, to theater or stadium organs.

The ancient hydraulis evolved into the pipe organ, with bellows for air compression. By the 8th century, if not earlier, pipe organs were already associated with churches and liturgical music. By the baroque era, the organ had reached great complexity. The very nature of the organ lends itself to the polyphony that is inherent to baroque music – and the baroque era was indeed the “Golden Age” for the pipe organ.

Each pipe produces a single pitch, and pipes are provided in sets called ranks. The pipes of a rank share a common timbre (tone) and volume. Most organs have multiple ranks, which can be played alone or in combination through the use of a control called a stop. There may be one, or more than one, keyboard, as well as pedal boards for the feet. The keys and pedals control different stops.

An organ can range in scale from a dozen pipes and one keyboard, to thousands of pipes and multiple keyboards and pedal boards. Large organs are physically integrated into the buildings that house them.

A factor that sets apart the organ from the other keyboard instruments is that the sound remains constant while the corresponding keys are pressed. On other instruments – such as the harpsichord, fortepiano, or modern piano – the sound begins to decay as soon as a string is plucked or hammered.

The organ repertoire is vast, having built over centuries. Even within this broad repertoire, however, the organ works of one composer stand out: Johann Sebastian Bach. Others who created notable organ works include George Frideric Handel,and Felix Mendelssohn.