Agathiyar once giving me a breathing technique in my Nadi, mentioned that both Lord Vinayagar and Buddha were the exponents and advocates of breath. Osho in his "Book of Secrets" mentions "Tantra is concerned not with any systemization of breath but with using breath just as a technique to turn inwards. Buddha tried particularly to use this method so this method has become a Buddhist method. In Buddhist terminology, it is known as Anapanasati yoga. Buddha's enlightenment was based on this - only this."
Similarly Agathiyar in asking us to go within asked us to use the breath as a tool. He told us to observe the breath. Ramalinga Adigal too came to remind us of that. Osho writes "Buddha said, "Be aware of your breath as it is coming in and going out." Eventually we shall take notice of the gap or interval between two breaths without effort. In bringing us Shivas first of nine techniques concerned with the breath, from the "Vigyan Bhairav Tantra", Osho in his "Book of Secrets" reveals, "If you can feel the gap Shiva says, the beneficence, then nothing else is needed. You are blessed, You have known; the thing has happened."
Initially, we are asked to look for a quiet place to practice conditioning the breath or breath control as in pranayama and specifically nadi suddhi. Later we are asked to just sit and watch it moving in and out. The breath begins to nudge us at the Ajna center. Soon with practice, it begins to nudge us even as we are attending to other chores asking for immediate attention. It can happen any time and you shall be forced to pay attention to it leaving all things aside.
Osho explains that contrary to our belief that the incoming breath and outgoing breath are running parallel as in parallel lines, they actually are one single breath, that in actuality flows in a circle. There is a point where the incoming breath turns and becomes the outgoing. Quoting another stanza of Shiva, we are asked to observe and realize this point of turning and become a realized soul. When the breath is static neither going out nor coming in, at this fusion point we are in our center. Agathiyar calls this center Suzhimunai. Each shall realize his center. It is the place where there arise energy and a feeling or unarvu that comes with it. "Know it to be your Suzhimunai," says Agathiyar. Osho asks us to observe the child breath. He says children are in their center and at their center. The reason being children give themselves up completely in all their doings and at all times. Hence we should learn to follow these children give themselves up in totality and not try to change them to our ways. One who arrives at his center becomes total. Agathiyar calls this the state of Paripuranam.