"The Sanskrit word diksha is formed of two syllables: di which comes from the root dan meaning to "give spiritual knowledge" (divya-jnana); and ksha from the root kshaya meaning "to destroy sinful activities." Diksha is the process by which a conditioned soul attains transcendental wisdom and freedom from sin." (Visnu-yamala)
Diksha is a process of spiritual initiation through which the guru imparts transcendental knowledge to the disciple. Diksha clears all previous bad tendencies and commitments. One begins a new life awakened in divine knowledge. By giving Diksha, Sri Guru mercifully slackens the bondage of maya, infuses transcendental energy into the disciple's heart, and awakens an awareness of his eternal relationship with Sri Hari.
"Diksha is that religious undertaking which bestows divya-jnana or transcendental knowledge and destroys papa (sins), papa-bija (seed of sin), and avidya (ignorance) to the root." (HBV) "Divya-jnana is transcendental knowledge contained within a mantra which reveals the form and identity of Supreme Lord (bhagavat-svarupa) as well as the knowledge of the sadhaka's particular relationship with the Lord (sambandha-jnana)." (Bhakti-sandarbha, anuc. 283)
By giving the Gopala-mantra (Krishna-mantra) the spiritual master dispels the jiva's aversion toward the Lord, and directs his attention toward serving Him. He gives the disciple transcendental knowledge about the Supreme Lord, the living entity, and the illusory energy. By this knowledge the disciple's sins and ignorance are all destroyed to the root. The procedure of Diksha is not completed in one day; rather, it starts from the day of initiation.
Sri Radha describes how one day in Goloka Vrndavana, Gopinatha’s coveted flute took mantra diksha: Srimati Radharani said, “My dear friend the flute, it appears that you have been born of a very good family, for your residence is in the hands of Sri Krishna. By birth you are simple and are not at all crooked. Why then have you taken initiation into this dangerous mantra that enchants all the gopikas of Vraja?” (Cc. 3.1.162) The next article will describe how to find and choose a Guru.
Excerpt from book Gayatri Mahima Madhuri by Mahanidhi Swami