Consider our life as it is with its crying and laughing. There is in each case a trace left; of crying it is a trace of crying, and of laughing the trace of that laughter. Our living leaves these traces. What I emphasize always is that even when it is laughter, we should laugh with a truly empty heart. But we never do so. ‘Cold today!’ and ‘Well, how are you?’—remarks which have no point, poured out like oil and accompanied with a little laugh. No real laughter of pure enjoyment, because even in our laughter the heart does not become empty of its burdens. The thing called the I is in the breast and the laughter is centred round that I. It is laughing because things seem well for the I. And the crying is of the same sort. With each step the track is left, and this way of life is the world of birth-and-death, the life of illusion.
The tracks left by joy or grief are footmarks. In religious terms, Zen master Dogen calls them the heavy burden of ignorance, root of evil. Though I die, the roots of the evil I have created are not annihilated. When he calls it a load, he means that all the time in our progress through life there is a great burden which is more than we can really bear, and shouldering it we are drenched in sweat, until finally our human life ends. We long somehow to put it down, by some means to lighten ourselves of the weight of conceptual thinking; but to do so we have to be earnest seekers. If we are not, there is no religion. The quest for inner lightness—to be able to cry but with an emptiness within the heart, to laugh but with the same emptiness—such is the great wisdom. To do things with an inner emptiness is the wisdom of the knowledge of ultimate Emptiness. The power of negating into emptiness is the great wisdom.
Only by completely negating our human living through wisdom-power is realization of the far shore possible. This is the Prajna Paramita. Only by ultimate Emptiness can we live each step of this frustrating life without a load on the heart, only then sport in the world of satori called Nirvana. Nirvana is translated ‘extinction’, but what extinction means is that even when crying the crying leaves no traces. Similarly, Emptiness does not have the meaning of a void with nothing in it. It means not leaving a track. At present each step is leaving a track, but if we can realize this trackless state, even in the present life, it is Nirvana.
To sum up: we are to pass over to the Nirvana state which leaves no track, by the power of the ultimate Emptiness of the Prajna Paramita wisdom. The way to do it is set out in the Heart Sutra. The practice is to cross to the world of Nirvana by the power of wisdom, and to train the heart to do it is what the Heart Sutra teaches.