Dhyana is the seventh limb of Ashtanga Yoga. Dhyana means worship, or profound and abstract religious meditation. It is perfect contemplation. It involves concentration upon a point of focus with the intention of knowing the truth about it. During Dhyana, the consciousness is further unified by combining clear insights into distinctions between objects and between the subtle layers of veils that surround intuition. We learn to differentiate between the mind of the perceiver, the means of perception, and the objects perceived, between words, their meanings, and ideas, and between all the levels of evolution of the nature. We realize that these are all fused in an undifferentiated continuum. One must apprehend both subject and object clearly in order to perceive their similarities, for a clear grasp of real identity of two apparently different things requires a clear grasp of their seeming difference. Thus Dhyana is apprehension of real identity among ostensible differences.