hi snookie. I think if you asked anyone who has delved into the study of yoga beyond just the physical practice of asana, they will be able to tell you that the historical teachings of yoga come to us through three main lineages, ie, the classical (samkhya) school, the vedanta, and the tantra. The philosophical differences are not minor. If you were to take your question one step deeper, and ask a certified Anusara teacher, you would get an even more interesting anwer. If you wanted to go the source materials themselves, you could check out any of the following books from your local university library: http://www.anusara.com/index.php?option=com_conte...

Hi Andrew. Ashtanga, like Iyengar, is also 'classical' in its philosophical orientation, rather than Tantric.