Who is Ratri devi? Is she same or different from Devi Kaali?
You must be knowing about Sri Chandi, which is also known as the DurgA Saptashati or the Devi MAhatyam and which is a part of the MArkandeya PurAna.
Now, a Chandi PAtha is considered to be flawed or incomplete if all the Shad-Angas ( the Kavachas, the Rahasya Trayas etc) are also not chanted along with. So, chanting simply the slokas of Sri Chandi is not enough. One who does so is said to be cursed by Devi.
And, it is also mandatory to chant two Suktas from Rig Veda as an allied part viz- the Rig Vedokta Devi Suktam (which is discussed in this answer to your another question) and the RAtri Suktam ( Rig Veda Mandala 10, Sukta 127).
A correct Chandi recital actually comprises of the following (in that order):
Sankalpa, Chandi PujA, Chandi Book PujA , NavAkshara Mantra japa (the ChAmundAyai Vicce one or the Tantrik 9-lettered mantra which is comprised entirely of Beejas), Argala stotra recital ( Jaya tvam devi ChAmunde etc), Kilaka recital, Devi Kavacham recital, RAtri Suktam recital, Devi Suktam recital (Om Aham rudrevir..).
Only thereafter Sri Chandi is to be recited. Now, all these allied recitals are Devi related. So, without any doubt the RAtri Suktam is Devi related and Goddess RAtri is an aspect of JaganmAtA , the Mother of the universe, who is praised in the Chandi.
The Sankalpa Mantra for the recital of RAtri Suktam, as a part of the Sri Chandi recital, is as follows:
RAtriti suktasya kushika rishih, rAtrir devatA, gAyatri chandaha, sri jagadambA prityArthe saptashati pAthAdau jape viniyogah |
For the RAtri Sukta, seer is Kushika, deity is RAtri, meter is GAyatri and, it is recited before reciting Saptashati, for pleasing the Mother of the universe (or Goddess DurgA).
Now, in the following mantra from the RAtri Sukta, there is no difference between Goddess RAtri and ParAshakti :
Ovarvapra amartyA nivato devyudvatah | JyotishA vAdhate tamah ||
The Eternal Goddess RAtri (or mahAmAyA) pervaded the whole creation, the small herbs and the tall trees with her Consciousness. And destroyed the ignorance (Tamah) by her illumination (JyotishA).
However, in these Mantras at one place, Goddess RAtri is described as having a sister called UshA and at another place she is said to be daughter of Supreme-Ether (ParamAtman).
Niru swasAramaskritoshasam devyAyati | ApeduhAsate tamah ||
The Goddess RAtri destroys the enveloping-power (avidyA) of her sister UshA ( swasAram=own sister). And in such a state of UshA, the veil of ignorance falls apart.
Upa te gA ivAkaram vrinishu duhitarddivah | RAtri stomam na jigyushe ||
O Goddess RAtri, Just like a milk cow (gA iva), i have appeased you, [by stuti-japa] (Akaram). You are the daughter (duhita) of ParamAkasha-ParamatmA (Duhitardivah). By your grace and blessings we will defeat our enemies like lust etc. Be pleased with our Hymns and Havi (offerings).
But Goddess KAli of the Tantras is the Supreme Parabrahman who does not have any sister and who obviously is the Eternal and the Primordial ( AdyA) one. So, she can not be born of something/someone.
On the contrary, it's from her, numerous universes take birth. Even the Trinities were born from her.
The same is stated by Lord SadAshiva to Sri AdyA in the MahAnirvAna Tantram:
Tvatto jyAtam jagat sarvam tvam jagajjanani shive ||
MahadAdyanuparyantam yadetat sacharAcharam |
tvayivotpaditam bhadre tvadadhinamidam jagat ||
tvamAdyA sarvavidyanam asmAkamapi janmabhuh |
The whole creation has evolved out of you. O Shive! You are the Mother of the universe. O Bhadre! From Mahat-Tattva till the atoms, the subtle-gross, the mobile-immobile-universe was created by you. The universe is under your supreme control and you are the primordial. All forms of knowledge and we all are created from you.
MahAnirvAna Tantram 4.10-12.
So, we can not really map the Vedic Goddess RAtri to the Supreme Goddess KAli of the Agamas. But we can reconcile. And in the following way:
It is well known that, Mother Goddess is also known by the name MahAmAya. Now, this MahAmAya can be of two types as said in the following verses:
SA mahAmAyA dvividA vidyAhavidyA cha |
YA mahAmAyA mukterhetubhutA sA vidyA |
YA samsArabandhanahetubhutA sAhavidyA ||
VidyA (Knowledge) and AvidyA (Ignorance) are the two forms of MahAmAya. The aspect which is the reason of liberation is VidyA and the one which causes worldly bondage is AvidyA.
So, we can map the VidyA aspect of Mother Goddess to the Vedic Goddess RAtri. Just like the opposites Alakshami-Lakshmi (viz-the Sri Suktam) are sisters so are VidyA-AvidyA and both of them are born of Sri AdyA (who is KAli, DurgA or Chandi etc). So, RAtri having a sister as well as being born, both facts are thus reconciled.
The MArkandeya PurAna also states the same:
SA vidyA paramA mukterhetubhutA sanAtani |
SamsArabandhahetushcha saiva sarveshareswari ||
The Eternal VidyA is Supreme. She is the mother of liberation as well as being the reason for worldly bondage (SamsArabandhana). And she is the Supreme controller of all the Godheads.
And, BTW, there is also another RAtri Suktam from the BrAhmanas. The Mantras from this Suktam alludes to a few more-known attributes of the Mother Goddess (like She is holding the PAsha, She being a Yuvati etc):
OM rAtrim prapadye punarbhum mayobhum kanyAm |
Shikhandinim pAshAhastAm yuvatim kumArini mAdityah ||
Srichakshashe vAntah prAnAya somo gandhAya Apah |
SnehAya manah anujyAya prithivai shariram ||
The MahAmAyA Goddess (RAtri Devi), who appears again and again (Punarbhum)[for the destruction of the Demonic forces], who is the giver of bliss-happiness to all beings, who is Shikhandini ( wearing a an ornament made of peacock feathers), who holds the weapon PAsha, who is Yuvati ( denotes the fact that she is devoid of childhood and old age and thus denotes her eternal nature) and who is the sum total of all KumAri etc Shaktis; I seek refuge in (prapadye) such Goddess RAtri. Let, by her grace, the Sun God protect my eyes (or beautify them) always, the God VAyu protect my five prAnas, the God Soma protect my sense of smell, the God Varuna protect all the fatty elements in me, the Moon God protect my mind and the Earth God protect my body.
SAmavidhAna BrAhmana, 3rd Mandala, 8th AnuvAka, 2nd Sukta.
This RAtri Suktam#2 is also chanted as an Anga of the Sri Chandi recital.
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