Yoga is a science. That is something to grasp. Yoga is a science, and not a vague, dreamy drifting or imagining. While it is true the west has been familiar with the practice of yoga for a relatively short time, yoga is not a new discipline , and it has been studied and practiced in many countries during the last century. Yoga is an applied science, a systematized collection of laws applied to bring about a definite end.
It takes up the laws of psychology, applicable to the unfolding of the whole consciousness of man on every plane, in every world, and applies those rationally in a particular case. This rational application of the laws of unfolding consciousness acts exactly on the same principles that you see applied around you every day in other departments of science. Yoga uses many of the techniques that are used in more modern and lately developed psychological or even medial physical exercise disciplines.
As one ages he learns that by looking at the world around you, how enormously the intelligence of man, co-operating with nature, may quicken "natural" processes, and the working of intelligence is as "natural" as anything else. The yoga way not only combines this feeling of “cosmos” but also works beneath the surface to strengthen the unity of man with the universe. We make this distinction, and practically it is a real one, between "rational" and "natural" growth, because human intelligence can guide the working of natural laws; and when we come to deal with Yoga, we are in the same department of applied science as, let us say, is the scientific farmer or gardener, when he applies the natural laws of selection to breeding. The farmer or gardener cannot transcend the laws of nature, nor can he work against them. He has no other laws of nature to work with save universal laws by which nature is evolving forms around us, and yet he does in a few years what nature takes, perhaps, hundreds of thousands of years to do.
This can b done by applying human intelligence to choose the laws that serve him and to neutralize the laws that have a negative effect on the goal of the farmer. The farmer brings the divine intelligence in man to utilize the divine powers in nature that are working for general rather than for particular ends.
Yoga is something that can make a real change in peoples lives, we have seen this many times, from the physical practice of yoga to the philosophical implications, through the knowledge of the science of yoga, all that is yoga combines into a bigger, complete discipline that is beneficial for humanity. For some calling yoga is a way to allow this to pass as a acceptable means of physical development, for others it seems like it contradicts the very spiritual nature of yoga, the different faces of yoga, as its different uses sometime creates the illusion of one single use.