The Rig Veda hymn 10:125 tells about the supreme Goddess. So is this hymn addressed to Goddess DurgA or the female power Of Universe (Shakti) Or vAk (वाक्), the speech? Who is vAk Goddess described in Rig Veda?
The eight Mantras of the Suktam in question were revealed to a female Rishi (or RishikA) called VAk, the daughter of Rishi Ambhrina. And, that is why it is called the VAk Suktam.
Another popular name of this Sukta is the
Rig Vedokta Devi Suktam.
It is customary to recite this Suktam as part of the Sri Chandi PAtha.
There are many Hymns in Rig Veda Mandala 10, where we find that the name of the Rishi is also the name of the DevatA. This Suktam is one such hymn.
This can be explained from the fact that in such hymns, the seer is completely one in consciousness with the DevatA. Other examples of such hymns being hymns of Vaikuntha (Rig Veda 10.48.50), Lava (Rig Veda 10.119).
Now, coming to the main question- Yes the Supreme Goddess is speaking through VAk in these eight mantras. You can call her (the Supreme Goddess) by names such as ParAshakti, ParamA Prakriti, Adi Shakti Or Sri AdyA or even by popular names like Sri ChandikA or DurgA etc or any other names of Mother Goddess.
The following is what the famous Vedic Scholar KapAli ShAstry writes about this Suktam:
Here in the case of Devi Sukta, the seer's realization of identity with the Supreme VAk, the creative word- which in the language of Tantra is ParAshakti- may account for the identity of the name (VAk as applied to the RishikA as well as to the DevatA).
It will be more correct to say that the female energy of the Supreme Godhead, ParAdevatA, realizing herself in or choosing the embodiment of VAk Ambhrini, utters the word, the Mantra.
From the "Complete works of KapAli ShAstry".
I am giving few mantras from the Devi Suktam with their translations below:
Om aham rudrebhir vasubhih charAmi, aham adityair uta vishvadevaih, aham mitrA- varunobhA bibhrami, aham indrAgni aham ashvinobhA ||
I walk along with the eleven RudrAs (Alt trans- I walk assuming the form of eleven RudrAs). I walk along with the VAsus (Or i assume the form of all the VAsus). I walk along with Vishnu and other Adityas (OR walk assuming the forms of the twelve Adityas) and the All-Gods (VisvadevA). I [assuming the form of the inner self of all Gods] hold aloft Mitra and Varuna. Even so Indra and Agni i do and the Asvin twins too.
Rig Veda 1.125.1
In the above mantra Devi declares Herself as the inner self of all Gods. She is all pervading and all permeating.
aham somam ahanasam bibhrami, aham tvashtAram uta pushanam bhagam, aham dadhAmi dravinam havishmate, supravaye yajamAnaya sunvate ||
I uphold and cherish the Soma that is pressed out (for the delight of the Gods). I am the upholder (or supporter) of Divine sculptor Twashtri and of Bhaga and Pushan too. I am the giver of the fruits of the sacrifices (that are done for pleasing the Gods). I am the one through whom the pleasing offerings of Soma and Havis reaches the Gods.
Rig Veda 10.125.2
In this mantra Devi declares herself as all powerful, the Parameswari, who is the only granter of all wishes and fruits of all sacrifices.
aham rashtri samgamani vasunam, chikitushi prathamA yajniyAnAm, tAm mA devA vi-adahuh purutrA, bhuristhAtrAm bhuri Aveshayantim ||
The Queen, I am the sole dispenser of wealth. Conscious, I am the chief or first among the Gods (for whom the sacrifice is meant). Such am i (the One) and the Gods have found me established in the many. permeating and taking possession of the manifold existence.
Rig Veda 1.125.3
In this mantra too, the Supreme Goddess declares Herself to be only dispenser of the riches. She is the most supreme among all Deities. All worship and Havis eventually reaches her. She is only one who is adored in all sacrifices and the eventual receiver of the Havi. One can see here a PurAnic or Agamic connection where too Goddess LalitA holds the undisputed supremacy among all Deities. She sits on a throne made of Vishnu and other Gods. She creates the Trinities out of Herself. She is constantly served by Lakshmi and Saraswati, the respective consorts of Vishnu and BrahmA and etc.
maya so annam atti, yo vipashyati yah prAniti, ya im shrnoti uktam, amantavo mAm ta upa kshiyanti, srudhi shruta shraddvinam te vadAmi ||
It is by Me (the sole power) that one eats his food, one sees, breathes and hears what is said. They that ignore me (with their thought not turned to me) run to ruin. Hear, i declare to thee, the truth of faith, hear.
Rig Veda 10.125.5
In this mantra Devi declares Herself as the BhoktA (one who eats, enjoys) the DrashtA (one who sees) etc and thereby declares Herself as the ParamAtmAn. It is by Her only one lives, one hears and one speaks. Even in Sri Chandi, Goddess Bhagavati's TAmasi shakti has been declared as being responsible for Mahavishnu's YoganidrA. So, its Goddess Herself who makes Vishnu to sleep.
aham eva svayam idam vadAmi, jushtam devebhir uta mAnushebhih, yam kAmaye tam-tam ugram krnomi, tam bramAnam tam rishim tam sumedhAm ||
Of my own accord i announce this truth, which the Gods as well as men strive to reach. One whom i love, i make him mighty, I make him BrahmA, Vishnu etc and other Gods , I make him the Rishis and also a man power of pure understanding (sumedhA).
Rig Veda 10.125.5
Here also Devi declares Her supremacy and declares Herself as the Sarva Jagat Iswari or the sole controller of all Gods and men. It's She only who grants BrahmAtva Or Vishnutva or Rishi-hood. She is the ultimate abode or goal that all Gods and men strive to achieve.
In the remaining mantras Devi declares that its only She who stretches the bow for Bhagavan Rudra to destroy the Veda-haters. Its She only who fights for Shadhu Janas ( the righteous ones) in times of need. Also, that its She who gave birth to AkAsha, the root cause behind the creation of all elements ( Mulakaranaswrupa of Sarva Bhutas) and to the Father of Heaven etc, And that She is independent, creates and dissolves universes out of Her own free will.
So, Devi is described in these eight mantras as the all powerful, all pervading and all permeating ParamAtAman who has become many from One. One in whom all Gods are situated. Who is the inner soul of all Gods and all beings. This concept is elucidated in greater details in the Agamas where Devi assumes the three forms viz- VAma, JyesthA and Roudri to accomplice the respective tasks of creation, preservation and destruction.
Relation to Tantra:
Durga saptashati, also known as Sri Chandi, is a litany of 700 verses occuring in the MArkandeya PurAna. The PurAna purports to be a dialogue between the sage MArkandeya and Kroshtuki.It is said that the Devi Sukta provides the Vedic basis for Sri Chandi. We get the clue from a line in the closing verses of the Saptashati where it is stated the Devi Sukta was being used for PujA.
Devisuktam param japam
We can conclude with the following words of KapAli ShAstry:
The reader could ponder over the mighty words of VAk and see if it is not in line with the high spirit and purpose of DurgA Saptashati.
So, VAk here is the Supreme Goddess, Sri Adi ParAshakti , the sole controller of Iswaras. The Mother of all.
As i have already told in the beginning, that it's mandatory (or customary ) to recite the Devi Suktam as a part of reciting Sri Chandi. Now, i have this very fat book called Sri Sri Chandi, which gives the following Sankalpa mantra to be recited before reciting Devi Suktam. And it mentions the DevatA for the Sukta differently.
Ahamityashtarchasya VAkAmbrni Rishihi Sacchitasukhatmakah Sarvagata ParamAtmA DevatA DvitiyAyA jagati ShishtAnAm Trishtupa Chandah Devi Sukta Jape Viniyogah ||
So, Sacchidanada swarupa, all pervading ParAtmA is mentioned as the DevatA for the Devi Suktam and who is of course Sri Adi PArAshakti.