Yajnyopaveeta Dhaarana :
Wearing three strands of ‘sacred thread’ makes a person eligible for the performance of all Vedic rites and the potency of mantras uttered helps the wearer attain the lusture (Brahma Tejas) induced due to clarity of mind attained from Vedic knowledge.
Yajnyopaveeta & Traditional Attire :
Yajnyopaveeta is worn by the Brahmacharis at the time of Upanayana and it gives the Brahmachari, the eligibility for the study of Vedas and scripture and performance of Vedic rites. The three strands of Yajnyopaveeta stand for the three qualities of Sattva, Rajas, and Tamas, which need to be kept in proper equilibrium for spiritual development.
A Brahmachari (Bachelor) wears three strands; a householder (married person) wears six or nine. The six strands give to the person the eligibility to perform the Vedic yajnas etc.
In all the traditional functions, be it individual worship, temple rituals, or worship of manes (shraddha, etc) the shastras prescribed the traditional attire of dhoti (plain white cloth wrapped around the loins extending a little below knee for Brahmachaaris) worn as Kaccha or Panchakaccha by householders along with an uttariya (upper garment). The right shoulder is always exposed; this again was to reiterate the commitment towards righteous i.e. dharmic path.
Brahmopadesha :
The word Brahma means God or Vedas. The learning of the Gayatri mantra makes a person eligible to learn Vedas and thereby attain Supreme Lord, hence the initiation of this Mantra to the child is called Brahmopadesha.
Paridhaana :
The child ‘Brahmachaari / Vatu’ has to completely surrender himself to his teacher at, worldly level and to the Supreme Lord ‘Savitaa’ at a philosophical level, in order to attain knowledge. The student has to shun his ego which would hinder his attainment of wisdom.
The appropriate age of Upanayana is prescribed as seven (garbhaashtama). After the performance of Upanayana, the Vatu or Brahmachaari’s lifestyle undergoes an enormous change. There are daily ablutions (religious duties) to be performed three times a day called Sandhyaavandana, fire worship (samidhaadaana), be regulated in food, sleep, and dress, etc. By following these regulations, the Brahmachari earns an enormous amount of credibility and respect in the society of learned.
Gayatri is considered to be foremost of all mantras and also called Guru-Mantra i.e. the eldest among all mantras. The first mantra into which any Hindu is initiated is the ‘Gayatri Mantra’.
There is a custom of Vidyaarambha or Aksharaabhyaasa i.e. learning the new script at the age of three or four, which is practiced before the performance of Upanayana. It is now done on Vijayadashami day. This is in keeping with the modern trend wherein education is secular and has detached itself from the pattern of Vedic education. This ceremony of Aksharaabhyaasa is not a Samskara but has been found mentioned in Maarkandeya Purana.
In between Upanayana and Vivaaha, the next major sacrament, we have other Samskaaras such as four Vratas, Keshanta, and Samavartana. Now, these rites are performed a day or two before Vivaaha i.e. marriage.