And it makes sense within the Yoga Sutra metaphysics as the goal is the separation between Purusha and Prakriti.
Philip,
It would probably be useful to separate the philosophy which Patanjali is speaking about from the science and technology which we refer to as yoga. Patanjali was speaking from a certain philosophical perspective - that everything in existence is dualistic, there is always a split between what one calls Purusha and Prakriti. Yoga, as a science, has little to do with any philosophy or belief system - in exactly the same way that modern science has little to do with any belief system. Yoga, as a method, is just pure technology. That is why Buddhists have been practicing the technology, Hindus have been practicing yoga, Sikhs have been practicing yoga, Jains have been practicing yoga, Charvaka atheists have been practicing yoga, because yoga
, as a method towards realization, just refers to the inner sciences towards ones enlightenment. It is just like learning how to use your computer, or learning how to use any other technology. So to me - it is very important that we do not mix up the two - that science and technology is one thing, philosophy is something else entirely. Yoga, as a science, has nothing to do with philosophy - it is cutting through all one-sided philosophies, belief systems, and coming to a direct perception of Truth. Truth is universal, it does not belong to any organized system of thought, and by it`s very nature, it cannot be organized. The mind can organize it, the mind can create countless interpretations about it, or the mind can also raise a finger to the moon - but the finger pointing to the moon is not the moon itself.