तत्त्वमसि (Tat Tvam Asi) is another Sanskrit phrase that can be translated as [[Well-Being - Seeker and the Sought|“You are That”]]. The sages of the Upanishads who discovered the core consciousness described above named it as the Atman. They also observed a similar phenomenon of constant change in the physical world around them. Instead of a world made of solid objects, they saw matter constantly coming together and separating again to change form. In their pursuit of finding an invariant, they defined an indivisible changeless reality underneath all things physical as the Brahman. Through their meditation, the sages discovered unity — the indivisible reality without us (Brahman) and within us (Atman) as one and the same. Thus, the multiplicity of all things living and material is rendered merely as an illusion.