" The adepts of certain forms of yoga affirm that most of the techniques appropriate to other ages are impracticable in the age in which we live, in which life is too short to bring them to fulfillment. The methods they propose as most suitable for the modem age can only be taught secretly, since they sometimes contradict religious and ethical concepts and taboos which are inherited from past times but whose value few individuals are mentally free to challenge.

[...] Yoga is often spoken of as though it were a system of exercises, physical culture for the mind and body. This is true to a certain extent in the preliminary stages connected with Hatha yoga. Although it is absolutely unnecessary to utilize this training to attain the highest forms of realization, it is such a great aid, such a useful preparation, that there seems no advantage to be had in neglecting it. "

― Alain Daniélou , Yoga: Mastering the Secrets of Matter and the Universe