Originally published in Tzvi M. Rabinowicz (ed.), The encyclopedia of Hasidism (1996), pp. 74-5. Hasidic thought follows the kabbalistic understanding of creatio ex nihilo (creation out of nothing, yesh me’ayin) in terms of the emanation of the Sefirot and the universe (of yesh, that which is) from Ein Sof (the Limitless, the Ground of Being), known…