 For Gelug the crucial point here, as Candrakīrti emphasizes, is that nirvāṇa is the truth strictly in terms of worldly conventions. Gelug recognizes this linguistic convention as a highly significant to the Prāsaṅgika system and it insists on conformity with the worldly conventions for the the following reasons. First, just as an illusion, a mirror image, etc., are real in an ordinary sense, despite the fact that they are deceptive and unreal, so, too, conventional phenomena in the Prāsaṅgika Madhyamaka sense are conventionally real, and can even be said to constitute truths, despite being recognized by the Mādhyamikas themselves as unreal and deceptive. Second, because the concept ultimate truth is also taken from its ordinary convention, nirvāṇa is spoken of as ultimate on the ground of its nondeceptive nature, in the sense that its mode of existence is consistent with its mode of appearance. The nondeceptive nature of the empty phenomenon itself constitutes its reality, and so it is conventionally described as ultimate in the Prāsaṅgika system.