A Tibetan Buddhist Perspective By Herbert Guenther, http://www.beezone.com/what_is_yoga.htm
The salient feature of this system is its emphasis on the so-called elements (dhatus) that constitute the prakrti (the multifaceted stuff the world is made of) in its conspicuously dual aspect of being "manifest" (vyakta) and "unmanifest" (avyakta) that in its Western transplant under the influence of the Cartesian bifurcation has been misinterpreted as the matter-mind duality. Starting from this fallacious premise with its hidden assumption that matter was evil and mind together with its figments was good, and applying this welter of misconception to what was deemed to be yoga, the word yoga has been defined as the union of the self with a or the supreme being and as a system of ascetic practices, meditative exercises, and other control mechanisms. designed to achieve this end.