A positive organ (pronounce "positeev"; also positiv organ, positif organ, portable organ, chair organ, or simply positive, positiv, positif, or chair) (from the Latin verb ponere, "to place") is a portable one-manual pipe organ that may be moved without first being disassembled. It was common in sacred and secular music between the tenth and the seventeenth centuries, when it was used in the performance of basso continuo parts in ensemble works. In the Middle Ages and the Renaissance, it was placed on a table or floor to be played, but many modern positive organs feature wheels. Before electricity, positives required a person to operate the bellows in order to supply wind to the instrument, but modern positives include electric blowers for this purpose.