Nana (echos)

In the theory and notation of byzantine music nana is the name of a special sign that denotes one of three things - depending on the historical period of the notation that it is used in or on the context:

1. It may denote a special kind of echos (mode) that is similar to the third mode but deviates from the diatonic scale followed by the third mode.
2. It may denote a modulation within another mode to an intervallic structure that is proper to nana (see below).
3. As theoretic treatises indicate, nana can have a meaning similar to that of a flat sign (b) in common western staff notation. However, this usage is hardly ever found in actual musical pieces.

Nana holds the status one of the two "special" additional echoi in the system of the Byzantine Octoechos. The other one is called nenano. Nana and nenano have been characterized in Byzantine theoretical treatises as both echoi and "not echoi, but phthorai". Phthorai are modulation signs and/or alteration signs. Theoreticians of various mostly yet unpublished treatises as for example codex EBE 899 of the National Greek Library in Athens, try to explain the difference between echos (mode), modulation, and alteration of diatonic degree, but these concepts are very difficult to explain without recourse either to a staff system notation, to a mathematical framework of ratios of frequencies of pitches, or to an experimental framework of lengths of sounding strings or pipes. Thus, the distinction between mode, modulation and alteration remains somewhat unsharp in the notational system. Based on EBE 899 and other texts it is possible to stipulate that nana may have in certain cases be understood as an attempt to provide a "flat" (b) sign lowering the pitch of a degree by a half tone or lesser interval, while nenano was its counterpart "sharp" (#). However, the actual use of nenano and nana was commonly not equivalent to that of flat or sharp signs. Instead, they indicate entire intervallic structures spanning a perfect fourth above or below the degree on whose sign they appear. Nana stands for an ascending tetrachord composed of tone-tone-halftone, and nenano stands for a tetrachord composed of halftone-augmented second-halftone.

The reform of the Byzantine neume notation in the early 19th century manages for the first time to clarify these matters as well as several other important aspects of the notation such as the duration of signs and associated questions of rhythm and meter. Chrysanthos of Madyta, one of the three persons that undertook the reform published a treatise explaining the principles of the new system, entitled "Theoritikon Mega tis Mousikis" (Great Theoretical Treatise on Music").

A published collection of Byzantine music treatises is found in Lorenzo Tardo's "L' antica melurgia byzantina".