In the life of a Hindu boy of the three communities, namely Brahmins, Kshatriyas, and Vysyas, Upanayana marks the beginning of Brahmacharya Ashrama which is set apart for the study of Vedas; this stage is said to be the second birth for him. Mere wearing of a sacred thread initiated on the Upanayana day does not make him a real Brahmacharin. It is rather the study of Vedas, learning and chanting Vedic mantras including Gayathri and Sandhyavandhana which will qualify him to be a true Brahmacharin. In modern education, there is no place for Hindu Scriptures and very few study Vedas after Upanayana. The least that is expected to be done after this ceremony is to recite the Gayathri mantra and do Sandhyavandhana. The ceremony is not given much importance or practiced with religious fervor by these communities. No attempt is made by the parents or the religious preceptors to educate the youngsters on the importance of this ceremony and its spiritual values. The ceremonies are done in a routine manner and the wards take this sacred religious ritual with least seriousness. The net result is complete ignorance and degeneration of values.
There possibly cannot be a better authority to enlighten us on Dharma Sastras and Vedas than the Maha Periyaval of Kanchi Kamakoti Peetham. The best explanation and thoughts on Upanayana.
"The upanayana of a boy is performed when he is old enough to understand things and chant mantras. During this ceremony, he is asked to go begging for alms. When he starts learning at the age of five, he will have basic knowledge of Sanskrit by the time he is eight years old, the age fixed for the Upanayana Samskara. The world will stand to gain if eight year old children wear sacred thread, have sufficient knowledge of Sanskrit and chant the Gayatri mantra."
"Upanayana means to take or lead the child near the Guru. Upanayana is initiation into the brahmacharyasrama and is the purvanga of student bachelor-hood. For students of krsna-yajurveda, there are four "vratas" between purvanga called Upanayana and uttaranga called samavartana. These are prajapatya, saumya, agneya and vaisvadeva. For Rig-veda, it is different; each Veda ha sits own Vratas. Everybody must learn his own veda and other subjects in addition. When we perform upakarma, we must start learning a new part of Vedas. Later at the time of utsarjana, it must be discontinued and the study of vedanga taken up. The vedas must be studied during the six months of Sraavana to Taisya. The next six months must be devoted to vedangas."
"To master the mantras, the student must strictly observe the rules pertaining to brahmacharya and to the particular part of the vedas that is being studied. The importance of the upanayana ceremony lies in this: it makes a person fit to receive instruction in the vedas and spread their divine power through out the world. Parents must realize this fact and perform their sons upanayana at the right time."