The "king of instruments" has a long history, one which can arguably be traced to the concept of a collection of "fixed-pitched pipes blown by a single player (such as the panpipes)" (Randel 583). The first examples of pipe organs with the basic features of today can be traced to the third century B.C.E. in the Greco-Roman arena; it is said to have been invented by Ktesibios of Alexander and contained "a mechanism to supply air under pressure, a wind-chest to store and distribute it, keys and valves to admit wind to the pipes, and one or more graded sets of fixed-pitch pipes." (Randel 583) These early organs used water as a means to supply air-pressure, hence the use of the terms hydraulic and hydraulis.
Hydraulic organs were in use for several hundred years before the concept of bellows, similar in concept and style to those of a blacksmith, came into use with the organ.
Numerous bellows were used to supply air to the wind-chest, often being pumped in pairs by men. The disadvantages of this method of air supply include the lack of consistent pressure, which leads to inconsistent pitch and tuning; also, many people were required to operate the bellows since there were upwards of twenty-four bellows per organ (Hopkins & Rimbault 35). Also, with organs of this size, the bellows took up large amounts of space, thus forcing the organ to be located in a fixed place, such as a church.
Up until the eleventh century (approximately), pitch and range of organs were extremely limited, mainly in part to the lack of a any style of keyboard. Keys of a sort were introduced around this time, though not in the manner we are accustomed to. "The earliest keyboards were sets of levers played by the hands...