When you sit in Chan, don't be greedy for flavorful Chan. What is flavorful Chan? It refers to the bliss of the Dhyanas. When you have been sitting just about long enough, you start experiencing a feeling of comfort and freedom, and you may feel kind of indolent. If you become greedy for this state of comfort and ease, it's not easy for you to go on and make progress. You will linger there, always trying to get back to the state of flavorful Chan. When the state goes away, you will chase after it, thinking, "When am I going to have that kind of state again? In that state there was no self, no others, no living beings, and no life span; no afflictions, and no hassles. It was very blissful and very comfortable and free. I wonder when I will ever have that experience again." And you will just keep waiting for that flavorful experience to reoccur. Waiting, you forget all about applying effort. That's known as getting attached to flavorful Chan.

Cultivators of Chan need to be free of obstructions and hang-ups. They cannot be craving anything. You cannot get excessively happy, or depressed, and you shouldn't have any fear or terror. You should see your body as being the same as empty space and the Dharma Realm. There's no need to cling to anything or crave anything. As soon as you crave something, you fall into a secondary level of truth. A brief explanation of the states of the Four Dhyana Heavens is given below.
The Heavens of the First Dhyana / The Stage of the Happiness of Separating from Production: leaving the afflictions of living beings, one obtains the happiness of "taking Dhyana bliss as food" and "being filled with the joy of Dharma." Leaving the confusion of living beings, one starts advancing along the Bodhi path of the sages. Arriving at the First Dhyana isn't something you can fake. It isn't something you can claim for yourself; a Good and Wise Advisor must certify the state for you.

When you reach that state, there is proof-the proof is that you no longer inhale or exhale-your breath has stopped, although you aren't dead. This is known as entering the Samadhi of the First Dhyana. It's different from sleep, so you shouldn't think that going to sleep is the same as entering samadhi. When you are sleeping, you continue to breathe, and you may even snore so loudly that it sounds like thunder to your neighbors. A Good and Wise Advisor can tell immediately whether or not your breath has stopped. If you say, "I feel like my breath has stopped!" that's false. You're faking it. If you know, then you haven't even entered the First Dhyana! So don't try to put up a false sign and sell counterfeit goods.

If I were to go into this in detail, there are a lot of principles that could be talked about, and I could write a whole essay on this. But if I say too much, it only creates obstacles. So I've just said a little bit to prevent you from becoming arrogant and misled by deviant views and claiming to have entered the First Dhyana (the Stage of the Happiness of Separating from Production). That's really cheating people.

The Heavens of the Second Dhyana / The Stage of the Happiness of Attaining Samadhi: The state of these heavens is one level higher, and not only does the breath stop, even the pulse stops. Again, you will not know it when you arrive at this state, and you cannot claim you have reached it. If you say you feel like you have, how do you know? You haven't even entered samadhi yet, so are you trying to fool people by faking it?

The Heavens of the Third Dhyana / The Stage of the Wonderful Bliss of Leaving Happiness: When you reach the state of these Dhyana Heavens, your breath, pulse, and even your thoughts will have ceased. In these heavens, you have left happiness and renounced flavorful Chan; you don't have the slightest attachment or greed for the comfort of flavorful Chan. This state is much higher than that of the first and second Dhyanas. All the hairpores on your body are blissful at that time. They are really, really delighted!

The Heavens of the Fourth Dhyana / The State of the Purity of Renouncing Thought: At this time there is nothing at all. "When not a single thought arises, the entire substance manifests." You reach that state where:

A thousand pools contain water,
The moon is reflected in all of them.
For ten thousand miles there are no clouds,
There are ten thousand miles of sky.

Everything is speaking the Dharma. "Falling flowers and flowing water proclaim the Mahayana." But you don't know it when you are in this state, and you can't say, "I've reached the Heavens of the Fourth Dhyana." That would be gross arrogance on your part, and you would be telling a big lie. One must be certified by a Good and Wise Advisor for it to count.
Why is a Good and Wise Advisor called a "clear-eyed person"? It's because he can take one look at you and know what your level of cultivation is. If you want to test him out, go ahead! But he won't pay any attention to you. A true Good and Wise Advisor will not be tested by you, and he won't tell you all the secrets just because you asked. You must draw near a Good and Wise Advisor for a long time, and then he may tell you, but not in a very obvious way. Sometimes he might use an analogy, or just say a few words. So you can't go around proclaiming, "We've all become Buddhas!" You would be telling a big lie and playing a huge joke, and in the future you'd fall into the Hell of Pulling Out Tongues. That's really pathetic!