“Avoid all evil, cherish all goodness, keep the mind pure. This is the teaching of Buddha.”
Dhyana is the stage of meditative trainings that lead to Samadhi.
Meditation is the work of consciousness aimed at the consciousness development along the path to Perfection and to the Mergence with the Creator. Meditation is practiced at three stages of the Patanjali’s scheme.
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.
At the dharana stage adepts among other things learn how to expand consciousness in the subtlest and the most beautiful that exists in the world of matter. By means of such attunement they establish in sattva guna. (And through working with Yidam they may immediately come in contact with the Fiery manifestation of Divine Consciousness and experience Samadhi).
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.
During dharana the mind is moving in one direction like a quiet river-nothing else is happening. In dhyana, one becomes involved with a particular thing - a link is established between self and object. In other words, you perceive a particular object and at the same time continuously communicate with it. Dharana must precede dhyana, because the mind needs focusing on a particular object before a connection can be made. Dharana is the contact, and dhyana is the connection.
Obviously, to focus the attention to one point will not result in insight or realization. One must identify and become "one with" the object of contemplation, in order to know for certain the truth about it. In dhyana, the consciousness of the practitioner is in one flow; it is no longer fixed on one subject as in dharana.