The fact that AchAryAl had not come to propound any thing new; but only to renovate the thing [*vEda matham*] that was existing before, becomes known even from a statement of a purAnA.
There are many purAnA-s and ithihAsA-s which claim our AchAryAl to be an avatAr of paramEshwara. In one of such purAnAs - the kUrma purAnA- in a context which describes,'when the kOlAhalam of kali [*yugA*] would peak, the IshvarA Himself would take an avatAr to contain the flow (pravAham) of adharmA', there appears a slOka as,
karishyathi avathAram svam shankarO nIla lOhitha: |
sroutha smArtha prathistArtham bhakthAnAm hitha kAmyayA ||
'Sroutha' refers to the one that closely follows the 'sruthi' or vEda. 'smAartha' points to dharma shAstrA which were blessed by the rishI-s based on the remembrance of their deep contemplation on vEdA-s. This saying of kUrma purAnA goes to describe that the shankaran who is also nIlakantan (shankarO nIla lOhitha:) chose to take an avatAr Himself (karishyathi avathAram svam) to re-establish the vEda-dhArma-shAstra (sroutha smArtha prathistArtham) due to His desire to do the good to His devotees (bhakthAnAm hitha kAmyayA).
It is important to note here that this slOka, instead of mentioning either the advaitha prathishtA or shanmatha prathishtA (the two important aspects which we associate with our AchAryAl, at the very mention of His name, nowadays) refers only to the sroutha smArtha prathistA.
Similarly, even in the slOka recited as AchArya vandhanA,
sruthi smrithi purAnAnAm Alayam karunAlayam |
namAmi bhagavadh pAdha shankaram lOka shankaram ||
there are references to sruthi and smrithi. Here also there is no mention about advaitham or shanmatham. But, it describes our AchAryAl as the repository of vEdA-s, dharma shAstrA-s and purAnA-s. If smrithi-s are those texts which formulate the laws based on vEdic dictums, then purAnA-s are those which convey the essence of vEdA-s through the medium of stories so that the mind could imbibe them. AchAryAl is described to be an 'Alayam' of this triad - sruthi, smrithi and purAnam.
As the very mention of 'vEda matham'or 'smArtha sampradhAyam' implies the advaitam which establishes the 'abhEdham' between the jIva and brahman; as the concept of shanmatham which emphasises the 'abhEdham' between all the dEvathA-s, is a part (angam) of advaita itself, it appears that there is no specific mention of either advaitA or shanmatham in this slOka as well as in kUrma purAnA.
shanmatham is a part of advaitA. If advaitA is mentioned, then there is no need to separately refer to shanmatham. When it is claimed that jIva and brahman are one, is it not implied in that, that all the dEvathA-s are also one, which is the 'thAthparyam' of the scheme of shanmatham ?
As shanmatham is a part of advaitam, advaitam is the part of smArtham and vaidhIkam. Amongst all the philosophies of vEdAs, advaitam occupies the highest position. We observe in vEdA-s, the view that all the devatA-s are indeed the very same paramAthmA. That is why advaitA and shanmatham are none other than the paths which completely follow vaidhIkam and smArtha sampradhAyam. Only following? [*No*] They are, verily, one and the same.
The very 'vaidhIka matham' implies advaitin's sampradhAyam. Advaita means only vaidhIkam. Does Sri HarshA not similarly substitute, advaitA where ever he has to refer to vEdA matham, in naishadham .
Therefore, all those who have not undergone the specific samskAram-s of dvaithA, vishistAdhvaithA and saiva siddhAntham are followers of sri Sankara Bhagavadh pAdhAl only. Even though they might have migrated to other sampradhAyam-s and left AchAryAl, it doesn't mean AchAryAl had left them. Accepting all those siddhAntham-s at different levels is His siddhAntham.
AchAryA's parama guru (guru's guru) Gauda pAda had written 'mAndUkya upanishad kArikA'. 'kArikA' is one of the types of bAshyam-s. (Even in Tamil, there is a work called 'yApparuNGalam'. The book that was written explaining the details of the former is known as 'yApparuNGalak kArikai'). GaudapAda says in mAndUkya kArikA that 'Many siddhAntham-s differ from each other and oppose one another. But, our advaitam never views any of them with a sense of enemity':
parasparam vrudhyanthE thairayam na vrudhyathE |
The path given by AchAryAl to us is this: an attitude which doesn't see any enemity, sense of oneness and 'samarasam'. We should always follow these.
Though we may be separated [while engaging in different types of*] actions which are prescribed by vEdAs, smrithi-s and later by AchAryAl and also in 'AchAram-s' which are required and conducive for carrying out those [*vEdic*] kAryAm-s, without entertaining any sense of difference in the mind, all of us should remain united through [*mutual*] affection, as AchAryA's children. Let us pray to AchAryAl Himself to do this anugraham [*blessing*] also.
. Sankara SampradhAyam - 16, deals with this topic in detail.