From the book "Naam or Word", written by Sant Kirpal Singh

In almost all the scriptural lore we come across, in one form or another, a term that stands for "initiation," i.e., introduction of a person into the principles of the inner science. The Muslims generally use the word "baet" for initiation, while others call it "deeksha." Among the Christians, the admission to the church is known as "bap­tism." The Hindus call it "duojanma" or the second birth.

This initiation or introduction into the tenets of a new science is not something formal or by word of mouth only. Its significance is far deeper than is generally under­stood. It is tantamount to adopting an individual into the very life and spirit of the tenets that are introduced to him in theory. It is conveying a Life-impulse to the initiate and giving him first-hand experience of the source of life. It thus has a two-fold aspect: theoretical as well as practical.

At the time of the initiation, the Master explains to the individuals concerned the theory of the spiritual science or Para Vidya (the Knowledge of the Beyond). It is an admitted fact that theory precedes practice, for a correct understanding of the subject is of paramount importance before one can put the theory into practice. A successful application and experimentation with verifiable results cannot be carried on without a correct knowledge and understanding of the subject.

As spirituality is the science of the spirit or soul – a Living Principle, the very Breath of Life – an adept in spirituality must impart to every initiate a particle of his own Life-impulse (called "Jia Dan") before the initiate can understand what the "life of the spirit" is, as distin­guished from the "life of the flesh" that he has been lead­ing hitherto; for it is the spirit or soul alone that can ap­prehend and experience the Oversoujl, when freed from the trammels of the flesh, the mind, the pranas or vital airs, and all the outgoing faculties, all of which constitute the outer man as engaged in the world and worldly pur­suits on the sensual plane.

By imparting his own Life-impulse, he instills true devotion in a person and unites him with the Lord.
GURU ARJAN