Within most pre-modern, Indian traditions of yoga, the role of the guru is absolutely central. Indeed, it was often understood that yoga would simply not work without the grace of the guru. The modern period saw the dawn of new, democratic, scientific modes of yoga practice and teaching. While teachings and gurus have always adapted to the times and circumstances, the sheer pace of cultural change ushered in by modernity has led to some unprecedented innovations in the way gurus present themselves and their teachings, and the way they are received by their students.