When the self dissolves in Atman, it is like when salt dissolves into water; this is Samadhi. When will dissolves in Anatman to like the non-action of unconscious breathing, when all samkalpas, all will, cease to exist, it is like when steam dissolves into air; this is Samadhi.
What is the property of water? Is it liquid like the salty ocean? Is it vapor like the morning fog? Even a vast ocean can be crossed on foot when frozen solid like the earth - and when the fog dews, it may be collected by a flower, and satisfy thirst. The form changes, but not its identity. What is form to the formless, time to Time? Call this "that" and that "this," it has no name until we declare it has one. What is the difference between one and nothing? Each are forms. Each are names: there are enough names. Still yourself in the bewilderment for but a moment: this is Samadhi.