By “Nature” he understood Buddha-Nature, or more particularly from the intellectual point of view, Prajñā. He says that this Prajñā is possessed by every one of us, but owing to the confusion of thought we fail to realise it in ourselves. Therefore we must be instructed and properly guided by an adept in Zen Buddhism, when we shall open a spiritual eye and by ourselves see into the Nature. This Nature knows no multiplicity, it is absolute oneness, being the same in the ignorant as well as in the wise. The difference comes from confusion and ignorance. People talk so much, think so much, of Prajñā, but fail altogether to realise it in their own minds. It is like talking about food all day, however much we may talk we forever remain hungry. You may explain the philosophy of Śūnyatā for ten thousand years, but so long as you have not yet seen into your Nature, it is absolutely of no avail. There are again some people who regard Zen as consisting in sitting quietly with an empty mind devoid of thoughts and feelings. Such know not what Prajñā is, what Mind is. It fills the universe and never rests from work. It is free, creative, and at the same time it knows itself. It knows all in one and one in all. This mysterious working of Prajñā issues from your own Nature. Do not depend upon letters but let your own Prajñā illumine within yourself. 2. The inevitable result of it was the “abrupt” teaching of the Northern school. The seeing is an instant act as far as the mental eye takes in the whole truth at one glance—the truth which transcends dualism in all form; it is abrupt as far as it knows no gradations, no continuous unfolding. Read the following passage from the _Platform Sutra_, in which the essentials of the abrupt doctrine are given: