The metaphysical foundations behind Patanjali's famous Yogasutra are critical for our appreciation of the work and the traditions that develop in the aftermath of the text. These claims and foundations of understanding are not addressed directly in the Yogasutra but are assumed and made part and parcel of the development yoga traditions in the works of every subsequent commentator. Here we look at these basic structures, assumptions, and claims of metaphysics that undergird the Yogasutra.