All of the Six Wonderful and Profound Dharma Gates can produce many kinds of dhyana. The first of these is attained by the practice of counting the breath, because, in this way, you will arrive at the Four Dhyanas of Form, the Four Immeasurable Minds and the Four Formless Dhyanas. When you have attained the last stage of Neither Thinking Nor Not Thinking is Not Nirvana,you have only attained The Way of The  Three  Vehicles,because this worldly Ch'an Tingis not yet real, still having some defilement. Using The Wonderful Dharma Gate of counting the breath and neither discriminating nor grasping, you can attain all three Vehicles at the level of Hinayana.

Following The Breath 
By this second practice, you can produce the Sixteen Special Dharmas:

1. When inhaling, knowing that you are inhaling;
2. When exhaling, knowing that you are exhaling;
3. Knowing when you are breathing a long or a short breath;
4. Knowing the whole body as the breath;
5. Knowing the movement of the body;
6. Knowing the delight of the mind;
7. Knowing the happiness of the mind;
8. Knowing mind activity;
9. Knowing comfort of the mind;
10. Knowing concentration of the mind;
11. Knowing freedom of mind;
12. Knowing impermanence;
13. Knowing all things (dharmas) as dispersed;
14. Knowing desirelessness;
15. Knowing nothingness or the property of vanishing;
16. Knowing what it is to abandon and give up everything.

Stopping 
If you practice stopping,you can obtain five kinds of dhyana, as follows:

1. Earth-Wheel Samadhi (which is not yet to have arrived at the tenth stage);
2. Water-Wheel Samadhi (which enables you to have good conditions for all kinds of dhyanas);
3. Space-Wheel Samadhi (which consists of five expedient ways of dhyana practice, whereby you come to understand space as being without any nature);
4. The Wheel-of-Golden-Sand Samadhi (which frees you from misleading views, so that you no longer grasp after right wisdom);
5. The Wheel-of-Diamond Samadhi (which is also known as The Completely-Without-Obstacles Tao,a practice that lets you sever your bondage to the three realms of desire, form and formlessness forever).

Furthermore, by stopping,you can attain Birthless Wisdom, whereby you can gain entrance to Nirvana.

Contemplation 
Through contemplation, you can take part in the Nine Thinkings, the Eight Lines of Thought, the Freedom From Eight Forms, the Eight Stages of Mental Concentration, the Ten Universals, the Samadhi of the Nine Degrees, the Samadhi of the Powerful Lion's Roar, the Transcendental Samadhi, the Practice of Ch'an, the Fourteen Transmutations of Mind, the Triple Bright Samadhi, the Six Transcendental Powers, and the Eight Liberations, all of which enable you to acquire the Samadhi of No-Sensation and No-Thought.

Returning 
The meditator, through Prajna, is freed of defilements by returning to the void of the Original Source, which is no source and in which there is nothing but void-without form and with non-action-indicating an absence of self-nature. Without any self-nature, there is no longer a subject or an object, and distinctions are no longer made because there is no one to make them and nothing to make them about.

In this way, the thirty-seven conditions leading to Bodhi are satisfied, as well as those contained in the Four Noble Truths, the Twelve Nidanas and in the Right Contemplation of the Middle Way, whereby Nirvana can be attained.

Purification 
If a meditator knows, through Prajna, that all Dharmas are originally pure, he can acquire the Dhyana of Self-Nature because he has attained what is known as Hinayana Nirvana, or Two- Vehicles Nirvana. If a Bodhisattva can enter the stage of the Iron-Wheel King, has completed the Ten Grades of Bodhisattva Faith and continues to practice, he can produce the following nine kinds of Great Dhyana:

1. Self-Nature Dhyana
2. All Kinds of Dhyana
3. Difficult Dhyana
4. All-Kinds-of-Doors Dhyana
5. Good-Person Dhyana
6. All-Active Dhyana
7. Rid-of-Defilement Dhyana
8. The-Joy-of-This-Life-and-The-Next-Life Dhyana
9. Pure-and-Clean  Dhyana  (Since  a  Bodhisattva depends on this kind of Dhyana,  he  can attain The Fruit-of-Great-Bodhi Nirvana)

In Sudden Enlightenment, the nature of mind is realized as being originally pure. Dharmas are neither grasped at nor rejected; there is neither being nor non-being; there is neither birth nor death; there is neither this nor that; and there is neither void nor existence, Then, there is the knowing afforded by the awareness of non-duality, where nothing is grasped, there being neither someone to grasp nor anything to grasp at. If Original Substance is known, there is freedom from attachment to the objects of the sense organs. Once there is no longer any illusion of the existence of a permanent self, there are no longer any encumbrances. There is no grasping at the void and no holding to stillness; there is simply whatever is, without defining or choosing. Short of this, there might still be a somewhat  encumbered level of awareness where there is a recognition of still being in the midst of causes and conditions, without attachment; but it is to be understood that even this recognition is a kind of grasping.

The Sastra of Entering The Tao of Sudden Enlightenment, by Ch'an Master Hui Hai of the T'ang Dynasty, asks what method should be used to understand Original Dharma. The reply is that one need only to practice dhyana. Referring to The Sutra of the Ch'an Door, one reads that if you seek the wisdom of the Buddha, you need Ch'an-Ting;for without it, you will have a great abundance of false thoughts and will be in danger of destroying your good roots. To understand this more clearly, Ch'an-Tingis defined as follows:  When there are no false thoughts, that is Ch'an; and to see one's Original Nature is Ting.Original Nature is also known as Non-Birth, or Unborn Mind, where there is no longer any oneto be moved by the eight winds of gain, loss, defamation, fame, praise, ridicule, sorrow and joy. Thus, even if one is worldly but attains Ting,he already approaches being a Buddha.

Elsewhere it is written that if you are free of attachment and if you no longer think of things (dharmas) during meditation nor discriminate between good and evil, then past things are past. If you do not think of them,  the mind of the past vanishes. This is called nopast. Furthermore, the future has not yet arrived; and when it is not necessary to wish to obtain it, the mind of the future is no more. This is called no future.Finally, the present is already present, and there is no need to grasp at anything. When you are free of thoughts, there is no longer any grasping. Without grasping, the mind of the present vanishes. This is called no present.Then your  mind dwells on nothing, and this is Original Mind and Original Nature. This Mind that dwells on nothing is the Mind of the Buddha, the Mind of liberation and the Mind of no-birth. Ch'an Master Kuei-Feng said that True Natureis neither pure nor impure and that there is no difference between the holy and the worldly.