The 15th century Hatha Yoga Pradipika called it a synonym of Siddhasana, where one of the heels presses the root of the repoductive organ; according to Yoga-Mimamsa III.2 p. 135, this explains the reference to the vajra weapon.[4] The 17th century Gheranda Samhita 2.12 describes what Light on Yoga calls Virasana, with the feet beside the buttocks, while in other texts Vajrasana appears to mean the modern kneeling-down position, with the buttocks resting on the feet.There is a four finger gap between the kneecaps, and the first toe of both the feet touch each other and sit erect.The reclining form of the pose, used in Ashtanga Vinyasa Yoga,[6] is Supta Vajrasana.[7] Laghuvajrasana, an advanced pose in Ashtanga Vinyasa Yoga and Iyengar Yoga, has the thighs raised halfway from the sitting position, the crown of the head on the floor and the hands grasping the ankles.