The One Suprme Divine Nature expresses Its will to redeem by assuming
a dual Spiritual Form - Narayana & Sri (Lakshmi) - these two aspects are philosophically inseparable but functionally distinct.
Sri (or Lakshmi) is related to Narayana as the fragrance is to a
flower, or the rays of the sun to the Sun.
Narayana with perfect justice rules the all the creation as supreme Father, but Sri His Eternal Consort resides within His heart as the embodiment of Saving Grace - the Universal Mother.
She ensures that the reign of righteousness is tempered by redemptive mercy.
The Lord dispenses justice in accordance with the merit and demerit of
the jiva and Lakshmi dependent upon the Lord, but through her Beauty and Grace she captivates the Lord and transforms his desire for justice (nigraha-shakti) into redemptive Grace (anugraha-shakti), she acts as the Mediatrix between the Lord and the jivas.
The Lord Narayana too is innately gracious, but His Grace is an “initial” Grace called kripa which is common to all higher beings. By virtue of this Grace, one is impelled to seek refuge in the Lord and become a servant of the Lord.
But the Grace of the Divine Mother (Sri or Lakshmi) is a specific Grace called prasada. It is the saving Grace; the response of ‘condescension’ of the Divine into the realm of being which permits the jiva to be liberated from Samsara.
The great theologian and Acharya Sri Vedanta Desika (13th century) finds all this potential for salvation implicit in the very name of the Divine Mother itself. The great Achraya derives six different meanings from the name Sri:-
sriyate - she who is resorted to by the jivas
srayate - she who resorts to the Lord Narayana
srnoti - she who listens to prayers
sravayati - she who causes the Lord to listen
srnati - she who removes the past karma, faults and hindrances in the way of the spiritual aspirant.
srinati - she who prepares the jivas for liberation.
This brings out the essence of Sri Suktam which part of Rig Veda.
Even in the Bhagavad Gita Krishna says that among women he is "Sri", though the interpretation by acharyas may vary.
kirtih srir vak ca narinam smrtir medha dhrtih ksama (Chapter 10; verse 34)
So, Divine Universal mother Lakshmi/Sri grants both material and spiritual prosperity including moksha/liberation.
Also, the term Lakshmi appears in Rig Veda:Sri Suktam, Rig Veda 10.71.2, Purusha sukta, also in bhoo sukta etc in vedas. Some of the instances:
Purusha suktha (Yajurveda recension) 2.6: hrishcate laksmisca patnyau
Rig Veda 10.71.2 : bhadraisam laksmirnihati vaci
Bhoo suktam: Lakshmi Priya sakihm devim namam acyutha vallbham and so on
Lakshmi is the term is popularly used to designate the consort of Vishnu.
Yaska the author of Vedic etymology,Nirukta, provides seven meanings to the term Lakshmi
Goddess is called lakshmi because she was acquired by Vishnu as his consort (laabhaa)
Goddess serves as an identification mark for Vishnu (lakshanat) i.e. the eternal
association of lakshmi with Vishnu makes the latter Supreme deity as distinguished from other vedic deities.
Lakshmi is one who grace is sought for material prosperity (lapsyanaat)
Goddess expresses her permanent presence on the chest of Vishnu (laanchanaat)
Goddess illumines the whole world with her lustre (lasate)
Goddess is called lakshmi because of her everlasting association with Vishnu (lagyate)
Goddess is very modest in the sense that though she grants all the boons (material, spiritual and liberation) to the devotees, she feels she hasn’t done enough for them(lajjate)
The same is echoed in Sri Stuti (verse 23) of the Great Acharya Sri Vedanta Desika (13 th century)
MAtA Devi! Tvamasi BhagavAn VAsudeva: PitAmE
JAta SsOham Janani YuvayOrEkalakshyam DayAyA: II
DattO YuShmatparijanatayA DesikaIrapyatastvam
Kim TE Bhuya: Priyamatikila SmEravaktrA ViBhAsi II
Oh Lakshmi (Devi)! You are my mother. Bhagavan VAsudeva alone is my father. I am but one among the numerous who have secured your grace and been blessed with your mercy. My Acharyas have given me to you in the form of an eternal servant. You are smiling at me now simply because you are thinking "what more is left that is befitting for Desika to
accomplish?" The tasks meant for me have been completed. This is what I infer from your smile.
Sayana interprets the term Lakshmi as the one who possess all the auspicious qualities (laksanavati)
- The common accepted definition is that Lakshmi is the one who shows concern for all living beings (lakksayatiti laksmih)
The greatness of the goddess lakshmi cannot be fathomed. This is wonderfully summarized by the Great Acharya of Srivaishnavism Sri Yamunacharya in Chatusloki Verse 2
yasyAstE mahimAnam Atmana iva tvadvallabhOapi prabhu:
nAlam mAtumiyattayA niravadhim nityAnukUlam svata: |
tAm tvAm dAsa iti prapanna iti ca stOshyAmyaham nirbhaya:
lOkaikeSvari lOkanAtha dayitE dAntE dayAm tE vidan ||
Oh undisputed Empress of the Universe! Oh dearest consort of the Lord, who s the Supreme ! Oh most merciful mother! Your greatness is limitless, natural/intrinsic and supportive in all matters relating to the activities of Your Lord. Even that Lord of Yours is unable to comprehend fully Your auspicious attributes just as He Himself is not able to measure His own immeasurable/infinite auspicious attributes.
Sri Periya VaacchAn PiLLai and Sri Vedanta Desika have commented with great insight on this and other slokAs of Sri YaamunAachrya’s Catussloki.
The Summum bonum of all this is that, Goddess Lakshmi, the universal mother grants everything from material prosperity, spiritual prosperity to moksha/liberation from transmigration.
Kubera though is a one of the asta digpalaka's is a lower deity and he is more of a holder of treasurer post, who is himself dependent on the Divine Supreme couple, Lakshmi and Narayana's grace.