The building blocks of Chan Buddhism

Buddhism is said to have traveled into China along the Silk Road in the first half of the first century AD. Its rise to prominence grew in proportion to the increasing traffic along the Silk Road, so that by the Tang dynasty (618-907AD) when China's capital, Chang'an, was one of the world's most prosperous cities, Buddhist translations were for the first time accessible. It was during this period that a new variant of Buddhism arose, which used elements from Daoism to beget a quintessentially Chinese variation of the Indian import. This new school came to be known as the Chan, or in Japan, the Zen school.
General concepts of Buddhism:
The general principles of Buddhism are evident in Chan Buddhism. That is to say that the world is an illusion conjured up by each individual's mind, that every thought has the power to produce a retributive future result (known as karma), and that it is this that decides what form we will appear in during our next life. Enlightenment occurs when we understand this, and nirvana is attained when we are emancipated from the endless cycle of life and death to join the Universal Mind. The main Chinese variations within Chan Buddhism are as follows:
1) The Theory of the double truth:
This defines two different kinds of truth, a common one and a higher one, on three different levels. At the heart of this complex theory is an examination of the inter-relationship between existence and non-existence. Truth is complicated by the fact that on the one hand there is physical form or existence and, on the other, everything is said to be illusory or non-existent. In which case, what and where is truth - within existence or non-existence? After considering this, the theory then considers the same question for enlightenment.
2) "A good deed entails no retribution". This idea stems from the Daoist belief in non-action, i.e. that action without effort, which is natural and spontaneous to the essence of the individual, does not entail any future retribution or "karma".
3) The method of attaining enlightenment is to do things without deliberate effort and purpose and live naturally. This (again linked to Daoism) prepares the mind for enlightenment.
4) That enlightenment occurs suddenly. Although non-action or living the life of non-cultivation diminishes distracting elements and facilitates contemplation, enlightenment itself is not a gradual process but a sudden revelation.
5) Although words can be a useful tool to explain a thought, they can only ever be an approximation to the idea. Thus, the state of enlightenment can never be described.
6) There is no other reality than this phenomenal world. Whereas the unenlightened only see the physical objects around them, the enlightened in addition to this see the Buddha nature within the phenomenal world.
This brief list of variations gives an impression of the far-reaching influence of Daoism on the synthesis of Chan Buddhism.