There is a separate school in Āstika tradition of Sanatana dharma as "Yoga". Also, the tantrik texts consists a section as Yoga itself. So how does the yoga as mentioned in Shad-Darshana differs from the one mentioned in Tantrik texts, both in terms of practise and philosophy? I once happen to see Swami Niranjanananda Saraswati of Bihar Yoga say "Tantra is the father of Yoga." So how did this system of Yoga originate in Tantra per se.