Developing a mode is like climbing a staircase. The artist works
from step to step, concentrating on the main note of each degree by
passages meant to emphasize it until he comes to the top note. From
there he quickly retraces his steps back to the starting point. If the
dastgah is the whole staircase, it is constructed in the steps of
several flights. These flights, the small, melodic, rhythmic or
free-rhythm sections, are called gusheh. Their names,
Pahlavi, Zabol, Khataj, Qajar. Etc. reveal their ancient origin and the
extensive contacts between Indo-Iranian, Chinese, Turkish and Mongolian
cultures through the centuries. A gusheh can last from about seven
seconds up to seven minutes, but, whatever the duration, it has to have
a beginning, a middle and an end according to a specific musical
formula. Within that formula, the rendition of a gusheh depends on the
musician’s art of improvisation. It is this art that is the life blood
of Persian music and the most difficult to master. There are about four
hundred gushehs distributed among the twelve modes, each gusheh having
a personality, mood and tonal color. A musician displays his artistry
in the particular number and combination of the gushehs he chooses to
play in a performance.