According to Mantra sastra, Upasaka has to embody himself for the Mantra he is chanting. This is what called as Nyasa. For that purpose, there are different methods, called as Anga Nyasa, Kara Nyasa, Rishyadi Nyasa, Hridayadi Nyasa, Panchatatwa Nyasa, Varna Nyasa etc. Though each one has its special benefits, Rishyadi Nyasa is famous. And each Mantra is recognised by the following – Rishi, Chandas, Devata, Beejam, Shakti, Tatwa and Keelakam.
1.Rishi: Believed as the one who got that mantra through divine vision (darshana) for the first time. The one who chanted that mantra and got benefits. For Durga Sapta Sloki, Narayana is the Seer. The Seer is the one who originally realized this knowledge and passed it along to us; a meter.
2.Chandas: Rhythm to be followed to chant that Mantra, very important for Veda mantras, not that much important for remaining mantras as they'll have only few letters in them. But, all mantras will be named traditionally with a Chandas. For Durga Sapta Sloki, Anushtup is the rhythms, which are 32 syllables to the verse.
3.Devata: Deity who appears by chanting that mantra. In Durga Sapta Sloki Srimahakali (remover of darkness) Srimahalakshmi (Goddess of Wealth) and Srimahasarasvati (Goddess of all pervading knowledge) are the deities. This will also satisfy and please Durga (reliever of Durgam-difficulties)
4.Beejam: Seed, which decides the route in which, the energy generated by chanting will be directed. It is the source, seed, and the algebra of the mantra.
5.Shakti: Energy generated by the mantra
6.Tatwa: Character of that mantra. Generally expressed in terms of Prithvi, Jala, Agni, Vayu, Akasa, Surya or Chandra
7.Keelakam: Door bolt. One cannot enter in to the room of results without opening it.
However, all these should be taken only as expressed forms of a mantra may not be mandatory.
In Sapta Sloki Durga
Shiva Uvacha, “Devi twam bakta sulabe sarva kariya vidayini, Kalau hi kariya sidya-artam upayam bhru hi yatnatah”
Devi Uvacha, “Shrnu deva prava kshiyami kalou sarva eshta sadanam, Maya tava-eva snehena piyambastuti prakash iyate”
1.Om jïäninä mapi cetäàsi devé bhagavaté hi sä balädäkrshya mohäya mahä mäyä prayachcati
2.Om durge smrtä harasi bhéti masesha jantooù svasthaiù smrtä mati matéva shubhäà dadäsi däridrya duùkha bhayahärini kä tvadanyä sarvopakära karanäya sadärdra cittä
3.Om sarva mangala mängalye shive sarvärtha sädhike sharanye tryambike devi näräyani namostute
4. Om sharanägata dénärta pariträna paräyane sarvasyärti hare devi narayani namostute
5. Om sarva svarüpe sarveshe sarva shakti samanvite bhayebhyaù strähi noo devé durge devi namostute
6.Om roogänaseshaä napahansi tushtä rushtätu kämän sakalän abhéshthän tvä mäshritänäà na.
7.Om sarva bädhä prashamanam trailokya syäkhileshvari evameva tvayä käryam asmad vairi vinähshanam