Further, Chandogyopanishad has an excellent explanation of the heart as"PADMAKOSHA PRATEEKASHA"--"YAD IDAM ASMIN BRAHMAPURE DAHARAM PUNDAREEKAM VESHMA DAHARO ASMIN ANTARAKASHAS TASMIN YADAA ANTAS TAD ANVESHITAVYAM TAD VAVA VIJIGNASITAVYAM ITI"
in this Brahmapur, city of God, our body, there is a tiny palace in the shape of a lotus(Pundareeka), within that is the inner Temple. What lies within that Temple, we should seek it.(tad anveshitavyam) We should seek to know it.(tad vava vijignasitavyam)
The Yogavasishtam cites the Chandogyopanishad and the Narayana Suktam as illustrating the atomic form of Sriman Narayana.
The sixth Anuvaka of Shikshavalli in Taittiriyopanishad tells that in the space inside the heart there exists an immortal golden being(Hiranmaya Purusha) and states that there is a subtle route, through the middle of the head through which a self-realized yogi travels when he/she leaves the body and joins the all pervading Brahman.
SRICAKRA AND BODY
Divine mother abides in sricakra. This is also known as sriyantra and Cakraraja. This is the most Supreme amongst all the yantras. Sricakra is the body of Shiva and shakti. sricakra is compared to a human body and Shiva and Shakti are compared to the soul within.
In Sricakra there are two Dasharas(antardasharam and bahirdasharam). If we imagine these two as one there are 8 cakras in Sricakra ,9 konas(angles), all the gods and godesses have a place in it. Supreme Point Bindu is in the centre. Jyotirmaya Kosha, Bindutattva and svargaloka are resplendent.
In the body of a sadhaka there are 7 cakras(mooladhara etc), if we include one from lambikagra it becomes 8, 9 randhras (holes of ears, etc.),the rulers of the senses Varuna etc., devatas are in the body. The Chandramandalam in the sahasrara cakra is resplendent. From agnacakra to sahasrara cakra it is jyotsnaloka i.e.,svarga(heaven). That's why it is said:
DEHO DEVALAYAH PROKTAH JIVO DEVAS SANATANAH
TYAJET AGJNANA NIRMALYAM SOHAM BHAVENA POOJAYET
It means our body is a Temple. The jiva in it is God. May one remove the impurities of ignorance by understanding self-(soham means I am he i.e.,I am Brahman) and worship the Lord.
Sadhaka, who performs antaryaga should not see any difference between the cakras in Sricakra and the cakras in our body.and should concentrate the mind on the Bindu in sahasrara cakra. While performing this type of yaga there is no need of rshi, nyasas, japa, etc. as in bahyapuja.