What do they exactly understand by “svabhâva” whose existence is denied in a particular object as perceived by our senses? This has never been explicitly defined by the Mahâyânists, but they seem to understand by svabhâva something concrete, individual, yet independent, unconditional, and not subject to the law of causation (_pratyayasamutpâda_). It, therefore, stands in opposition to çûnyatâ, emptiness, as well as to conditionality. Inasmuch as all beings are transient and empty in their inherent being, they cannot logically be said to be in possession of self-essence which defies the law of causation. All things are mutually conditioning and limiting, and apart from their relativity they are non-existent and cannot be known by us. Therefore, says Nâgârjuna, “If substance be different from attribute, it is then beyond comprehension.”[80] For “a jag is not to be known independent of matter et cetera, and matter in turn is not to be known independent of ether et cetera.”[81] {172} As there is no subject without object, so there is no substance without attribute; for one is the condition for the other. Does self-essence then exist in causation? No, “whatever is subject to conditionality, is by its very nature tranquil and empty.” (_Pratîtya yad yad bhavati, tat tac çântam svabhâvataḥ._) Whatever owes its existence to a combination of causes and conditions is without self-essence, and therefore it is tranquil (_çânta_), it is empty, it is unreal (_asat_), and the ultimate nature of this universal emptiness is not within the sphere of intellectual demonstrability, for the human understanding is not capable of transcending its inherent limitations. Says Pingalaka, a commentator of Nâgârjuna: “The cloth exists on account of the thread; the matting is possible on account of the rattan. If the thread had its own fixed, unchangeable self-essence, it could not be made out of the flax. If the cloth had its own fixed, unchangeable self-essence, it could not be made from the thread. But as in point of fact the cloth comes from the thread and the thread from the flax, it must be said that the thread as well as the cloth had no fixed, unchangeable self-essence. It is just like the relation that obtains between the burning and the burned. They are brought together under certain conditions, and thus there takes place a phenomenon called burning. The burning and the burned, each has no reality of its own. For when one is absent the other is put out of existence. It is so with all things in this world, they are all empty, {173} without self, without absolute existence, they are like the will-o’-the-wisp.”[82] _The Real Significance of Emptiness._