Mystic expression and interpretation has always been a challenging issue in the field of mystic language. This challenge, which stems from the inadequacy of language in dealing with mystic experiences, has led to the mystic application of the artistic possibilities of language. One such possibility is allegory. This article studies the allegories of light and water as two of the most significant allegories regarding the concept of ' the unity of being' in Mathnavi. In addition to denoting the existential concept of ' the unity of being' (the relation between truth and individuals), these allegories cover many of the other features of this notion. Relying on the uncountable nature of light and water, this research explores the capability of these allegories in mirroring the semantic clusters of the experience of unity. Among the issues that these allegories reflect are the paradoxical relations between such dichotomies as unity and division, appearance and reality, similarity and difference, the concept of the perfect man, mortality, and the theory of constant creation.