Acquiring the atharvaveda either requires you to be born as a scion of the atharvan clan or acquire it through a separate upanayanam. The key to this new upanayanam is the need for the student to chant the sUktaM known as triShaptIyam (AV-S 1.1 or AV-P 1.6). Only by chanting the triShaptIyam does the power of the atharvanic mantras enter him so that he can use them. Thus the triShaptIyam is also used before commencing practice of atharvanic recitation or svAdhyAyaH. For deploying an atharvanic spell for protection one needs the first mantra of the triShaptiyam to be recited. In the atharvanic upanayanam there is a special ritual apparently not seen in other vedic traditions. The father or teacher ties feathers of a shUka (parrot), a sAri (myna) and a kR^isha (Wren warbler) with a yellow string around the students neck. Then these are offered in the sacrificial fire with the triShaptIyaM. In a more gory shaunaka rite of the past the tongues of these birds were similarly tied and eaten. This qualifies him to start acquiring atharvanic vidya.
ye triShaptAH pariyanti vishvA rUpANi bibhrataH /
vAchaspatir balA teShAM tanvo adya dadhAtu me //1//
Three times seven that go around, bearing all forms;
let vAchaspati put their powers into my body’s [parts]
punar ehi vachaspate devena manasA saha /
vasoShpate ni ramaya mayy evAstu mayi shrutam //2//
Come here again vAchaspati with the mind of the devas;
lord of riches, make it stay in me, in myself the shruti.
ihaivAbhi vi tanUbhe ArtnI iva jyayA /
vAchaspatir ni yachhatu mayy evAstu mayi shrutam //3//
Just here stretch on, like the two ears of the bow with the bowstring;
Let vAchaspati hold in me, in myself the shruti.
upahUto vAchaspatir upAsmAn vAchaspatir hvayatAm /
saM shrutena gamemahi mA shrutena vi rAdhiShi //4//
vAchaspati is called upon, on us let vAchaspati call;
may we united with the shruti and not parted from the shruti.
The key rahasyas here are: the jaws are the Artni-s of the bow (1.1.2) and the vocal cords are the jya or the bow-string.
The first mantra gives the most reduced form of the sounds of saMskR^ita. It is from this most condensed set described as 3*7=21 that all sounds of the shruti are derived by knowning this (as the mantravit-s know it, not the plebeian) one gains the profound insight of the shruti. Hence the kaushika calls it the medhAprajanana mantra.
Thus we have:
1) a -> A
4) R^i->R^I, L^i, L^I
8) au = all above svara
10) ya, 11) ra, 12) la, 13) va =anthaHstha (half vowels)
14) ka->kha, ga, gha
15) c-> cha, ja, jha
16) T->Tha, Da, Dha->La
17) ta-> tha, da, dha
18) p->pha, ba, bha= all above sparsha
19) sa->sha, Sha = sibilants
20) ha = UShman
21) M->anunAsika+ma, na, Na, ~na, ~Na = nasals
Thus the atharvan tradition condenses all the sounds of Chandas to a set of 21 that are invoked to enter you in the triShaptIya rite. This marks the beginning of Hindu linguistics where the principle of homologous condensation was recognized. This is summed up by pata~njali in his mahAbhAShya thus:
avarNAkR^itir upadiShTA sarvaM avarNa-kulaM grahIShyati, tathevarNAkR^itiH tathovarNAkR^itiH |
The theoretical form of the a sound, when being taught, with contain the whole family of a-like sounds, so also with the theoretical forms of i and u sounds. Thus, the principle of homologous reduction stems from the root of the vedic tradition itself and made explicit in atharvanic education.