How many of the pilgrims, who reaches the Sanctum of Ayyappa, reads this message there?
Thathwamasi - has nothing to do with the word "Thathuwam"..
It is one among the four Mahavakyas of the Vedhas... Mahavakyas are the grand utterances of the Upanishads. The Final truth expressed in the Vedhas.
They contain the essence of the Vedanta and the ultimate truth. There are mahavakyas for all the four vedhas and everything convey the same meaning of Advaithic Truth.
The term Thathwamasi appears in the Samavedha - in the Chandogyopanishat.
Its a combination of three words
Tat Twam Asi = Thou art you. ie That is you
Tat - That
Twam - You
Asi - becoming / is
Here "That" refers to the Supreme being... ie Iam same as the supreme being
Understanding that we are not ordinary mortals - but we are the ultimate; this is Thathwamasi.
Tatvamasi is the fulfilment of spiritual knowledge. There is no second - "Iam that Supreme Entity"
This complex adwaithic wisdom is made simple in Ayyappa Thathwam... The State of Oneness... Thats the reason, once we wear the maala, we are taught to see everything as Ayyappan and everyone as Ayyappan.
Though we just call it outwardly and most of us never try to put the theory "everything is Ayyappan" into practice..
Just imagine the situation if it is in reality... "Every being is Ayyappan" "Every Devotee is Ayyappan" "Every piece of rock and mud is Ayyappan"... Now there is no question of "I" here... because even "Iam Ayyappan..." ie "Iam that Supreme Entity" ie "Thathwamasi"
Actually this (Thathwamasi and other) Mahavakyam is given as upadesham only while taking Sanyasam... Kanchi maha Swamigal said:
"It is to attain this highest of states in which the individual self dissolves inseparably in Brahman that a man becomes a sannyasi after forsaking the very karma that gives him inward maturity. When he is initiated into sannyasa he is taught four mantras, the four [principal] mahavakyas."
But Ayyappan is in Yoga Peetam at Sabarimala; He is a gurunathan there. Thats the reason he explicitly teaches this Maha Vaakya Saaram ie Thathwamasi with his Chinmudra...
Mahayogapeeto jwalantham mahantham
Mahavaakya Saaropadesham Sushaantham
Maharshi Praharsha pradham gnana kaantham
param jyoti roopam bhaje bhoothanatham