The hermeneutics of two truths is central to Madhyamaka dialectics and its deconstructive analysis of key metaphysical concepts, including those of causation, essence, and the self. In the Fundamental Wisdom of the Middle Way (Mūlamadhyamakakārikās; hereafter MMK), Nāgārjuna extends the notion that phenomena lack intrinsic existence (svabhāva) to apply to the self, which is usually conceived in dependence upon the five aggregates (MMK, IX, 12). While considering various ways of conceiving of the self (viz., as distinct from the psychophysical aggregates, as unchanging, as a unifying principle, or as an agent), Nāgārjuna concludes that none of them actually make sense on account of the fact that nothing can be said to be prior to the cognitive activities of seeing, hearing, etc. (MMK, IX, 7, 10). A metaphysical self, conceived as an abiding and substantive entity, is therefore inconceivable.