The ultimate goal of yoga is union of the individual with the higher Self and, thereby, the universe. It is a state associated with samadhi in general – the eighth and final limb of Ashtanga yoga as described in Patanjali's Yoga Sutras. Yoga practices such as asanas, pranayama, mudras and meditation are designed to help the yogi reach this ultimate state of spiritual union.
Some traditions believe that samadhi is synonymous with enlightenment, while others believe it leads to enlightenment. Still others believe it is a state in which the mind goes blank, freeing the yogi from all thoughts. Savikalpa samadhi is a state in which the mind is still active and the yogi is still attached to the bodily and worldly distractions, but he/she gets a glimpse of bliss.
In the highest level of samadhi – called nirvikalpa, sahaja or asamprajnyata in different traditions – the mind is under control and no longer imagines or wishes for anything. Only complete awareness remains. The yogi no longer sees differences because he/she sees the oneness and perfection of everything. The yogi's awareness withdraws from the three bodies – the physical, astral and causal – until he/she achieves oneness with the higher Self.