 Adherents believe Surat Shabda Yoga has been expressed through the movements of many different masters.However, a basic principle of Surat Shabd Yoga's tradition is the requirement for an outer Living Master to initiate followers onto the Path.The movements whose historical Satgurus have died and their successors do not purport themselves to be Surat Shabd Yoga Satgurus, usually are not considered currently to be Surat Shabd Yoga movements, either by their own leaders or by movements with current Living Masters.