One of Tsongkhapa’s greatest insights was his understanding of voidness (emptiness) to mean dependent arising and dependent arising to mean voidness. Voidness is the total absence of impossible ways of establishing or proving the existence of something. Specifically, in the context of the Prasangika Madhyamaka tenet system, voidness is the total absence of the existence of something being established by virtue of anything on its own side. The existence of something can only be established by virtue of dependent arising.
In other words, from a superficial point of view, nonstatic (impermanent) phenomena arise dependently on causes and conditions, and they produce effects. These two facts establish or prove that such phenomena exist. From the deepest point of view, the only thing that establishes that anything – either static or nonstatic – exists is that it is merely what the words and concepts for it refer to. Nothing can be found on the side of anything that establishes or proves that it exists.
The fact that everything is dependent in this way eliminates the “eternalist” extreme. This is the extreme that, in terms of the deepest truth about anything, the existence of something can be established independently, from its own side, by its own power. The fact that everything nevertheless arises eliminates the “nihilist” extreme. This is the extreme that, in terms of the superficial conventional truth about anything, nothing exists or functions at all.
Thus, by teaching dependent arising, the “King of Reasonings,” Buddha eliminated the two extreme wrong views concerning voidness and established the two truths about everything. Buddha even summed up the Four Noble Truths by his teaching of dependent arising. Samsara and its suffering (the first noble truth) arise dependently on unawareness (ignorance) of voidness (the second noble truth), as elaborated with the “twelve links of dependent arising.” The attainment of a true stopping of samsara (the third noble truth) arises dependently on understanding voidness (the fourth noble truth).
In his eulogy “In Praise of Dependent Arising,” Tsongkhapa gives poetical expression to his enormous appreciation of Buddha’s kindness in teaching dependent arising, which has all these outstanding features.