In Advaita Vedanta, it is said that the world is a manifestation/appearance of Brahman like ornament (world) and gold (Brahman) in gold-ornament metaphor. A hearer is puzzled as to how can the material world be envisaged as a manifestation/appearance of Brahman which is of the nature of pure existence (Existence) and is non-material. Existence is not perceived, world is perceived, whereas both gold and ornament are perceived. In this sense, the hearer argues that there is a disconnect of the gold-ornament from Brahman-world.
The counter argument from a co-hearer is that a metaphor is never similar to the thing illustrated for otherwise it ceases to be a metaphor. The principle is that in a metaphor, similarity is the focus and dis-similarity is ignored. In the instant case, dis-similarity due to material and non-material is ignored. What is the similarity then? Here comes the concept of mithya, i.e., neither nor unreal. Brahman is of the nature of Existence. It lends existence to the world which has no independent existence as it continuously changes. Brahman is real and world is mithya (ब्रह्म सत्यं जगन्मिथ्या). In the gold-ornament metaphor, ornament has no existence separate from that of the gold. Gold is real and ornament is mithya. Thus, there is a similarity (of mithyatatva)  between the illustration and the illustrated.
Agreement: In the gold-ornament metaphor to explain that the world is a manifestation/appearance of Brahman, the focus is on mithyatatva.