The very thought that an idea/philosophy, concept or some Shastras can remove darkness is wrong.
None of the these create the darkness (Avidya or ignorance). So,they are not capable of removing it either.
If you think study of Shastras etc can dispel the darkness then you are mistaken.
Na VedAh KArnam MukterdarsanAni Na Karanam |
Tathaiva sarva ShAshtrani
Gyanameva hi Karanam ||
Veda is not the reason for mukti (liberation),neither are the
Philosophies (the six Darshanas) and nor are the other Shastras.
Knowledge (of Paratatva,BrahmaGyana ) is the only mode for liberation.
MuktiDa GuruVAgeKA VidyAh SarvA VirambakAha |
KAshthaBhArasramAdasmAdekam Sanjeevanam Param ||
Only Guruvakya (the words of Guru) is the giver of liberation. Without
Guru upadesha all Vidyas deprive us.
KulArnava Tantram ,Chapter 1,Verses 106 ,107
The Upanishads also tell us the same thing:
NAyamAtmA Pravachena Labhyo Na MedhayA Na BahunA Srutena|
Atma(or BrahmaGyana) is not obtained by Pravachana(discourses on
Shastras),not by intellect(or by intellectual methods) neither by
listening to a whole lot of Shastras.
Mundaka Upanishad 3.2.3
Na NarenAvarena Prokta Esha Suvigyo VahudhA ChintyamAnaha|
Gatiratra NAsyaniyAn HytharkyamanupramAnAth||
BrahmaVidya should be obtained only from a Guru who is himself
BrahmaGyani. Brahmagyana (or self realization) is not obtained from that
Guru's upadesha who himself is not self realized.
And, if you think that adhering to a particular philosophy will help you in dispelling the darkness ,then also you are mistaken.See the following verse :
Advaitam Kochidicchanti Dvaitamicchanti ChApare |
Mama Tatvam Na Jananti DvaitAdvaitavivarjitam ||
Some are the followers of Advaita, some others of Dvaita. But none among
these know by my true nature which is beyond (or devoid of) both
Advaitic and Dvaitic principles.
KulArnava Tantram , Chapter 1, Verse 110
Only Sadashiva , in the form of a mortal/physical Guru , can remove the darkness. Because he himself creates the darkness (mala, avidya or whatever you call it) so only he himself is capable of removing it too.
In fact,your physical Guru and my Guru might not be the same apparently, but in truth both are Sadashiva only.
Ataeva Shivaha SAkshAd Gururupam SamAsritaha |
Bhaktya Sampujito Devi
Bhuktim Muktim Prajacchati ||
So,hey Devi, Shiva takes the mortal form of a Guru. Worshiping him (the
Guru) with devotion results in both Bhukti (material pleasures) and
Kularnava Tantram 13-52 .
ManushyacharmanAvaddhah SAkshAt ParaShivaha Swayam |
SacchiYAyAnugrahArthAya Guram ParjaTathi Khsithou ||
The ParaShiva himself comes in disguise of a human being and roams
around secretly to do his favor on the disciples.
Sadbhakta Rakshnayaiva NirAkArohapi SAkritihi |
SamsAriva Hi Chestathe ||
Compassionate Shiva is without form but still to protect true
devotees he comes on earth and behaves like mortal.
KulArnava Tantram 13-54,55
Guruh SadAshivah SAkshAt Satyameva Na Samsayaha|
There is no doubt in the fact that Guru is none other than Sadashiva.
In Mahanirvana Tantram , its further stated that during each initiations, Sadashiva comes in the respective Gurus and speaks the mantra unto pupils' ears and thereby dispels their ignorance.
So,Guru has to be living person, a physical one.
But , in exceptional cases, a Guru can be anyone or anything who/that teaches you something. This was the case with Lord Dattatreya who had such 24 unconventional Gurus.
In the Uddhava Gita, a song embedded in the Bhagavata Purana
(11.7-9), Dattatreya tells King Yadu about his 24 unusual gurus:
1. The Earth
The Earth is disrespectfully trodden on by all creatures but bears
them all without complaint. So from Her, I learned to accept all of
life’s pleasures and pains with forbearance.
2. The Wind
Wind is of two types, Prana refers to the internal life forces and
Vayu refers to the external movement of air. Prana is in all bodies
but takes on the shape and form of the particular body it is in. Vayu
passes everywhere but does not remain in one place. So from Prana and
Vayu I learned to avoid attachment to any place but to adapt to
wherever I might find myself.
Akasha is one and all-pervading. From it I learned that Brahman is one
Water purifies and sanctifies. From it I learned to be a source of
purity and sanctity.
Fire burns things leaving only their essence. From it I learned that a
yogi should see in beings not all the false opposites like rich-poor,
old-young, high-low, but only the Atma which is the essence.
The one and same moon appears to go through changes, waxing, waning
etc. From Him I learned that the one atman only appears to go through
changes such as birth and death.
You can learn about Lord Dattatreya's 24 unusual Gurus and what he learned from each of them from this booklet.