Chan Buddhism, also known as Original Chinese Zen, is a school of Buddhism that originated in China and is known for its emphasis on meditation and direct experience of enlightenment. The main teachings of Chan Buddhism can be summarized as follows:

1. Emptiness: Chan Buddhism teaches that all phenomena are empty and devoid of inherent existence. This concept is central to the Buddhist belief in impermanence and the interconnectedness of all things.

2. Non-duality: Chan Buddhism emphasizes the non-dual nature of reality, where there is no separation between self and others, subject and object, or mind and matter. This teaching encourages practitioners to let go of dualistic thinking and see the world as it truly is.

3. Mindfulness: Mindfulness is a key practice in Chan Buddhism, as it involves being fully present in the moment without judgment or attachment. This allows practitioners to cultivate a clear and calm mind, which is essential for achieving enlightenment.

4. Meditation: Meditation is the cornerstone of Chan Buddhism, and it is seen as the most effective means of attaining enlightenment. In Chan, meditation is not seen as a means to an end, but rather as a way of life.

5. Direct experience: Unlike other schools of Buddhism, Chan emphasizes the direct experience of enlightenment over the study of scriptures and intellectual understanding. This means that practitioners are encouraged to let go of concepts and theories and instead focus on their own direct experience of reality.

6. Non-attachment: Chan Buddhism teaches that suffering arises from attachment to desires and expectations. By letting go of attachments, practitioners can free themselves from suffering and achieve inner peace.

7. Non-verbal transmission: In Chan Buddhism, the teachings are often transmitted through non-verbal means, such as gestures, actions, and silence. This is because the ultimate truth cannot be expressed through words or concepts, but must be experienced directly.

In conclusion, the main teachings of Chan Buddhism revolve around the concepts of emptiness, non-duality, mindfulness, meditation, direct experience, non-attachment, and non-verbal transmission. These teachings aim to help practitioners let go of delusions and attachments and experience the true nature of reality, leading to enlightenment and inner peace.