This was given a mention in the overview, but I thought I'd expand on it further.

Conditioned Arising (paṭicca-samuppāda in Pali, also known as 'Dependant Origination') is a Buddhist doctrine strongly linked to the Four Noble Truths. In its abstract form, it states:

"That being, this comes to be; from the arising of that, this arises; that being absent, this is not; from the cessation of that, this ceases."

In other words, it states the principle of conditionality, whereby all things, mental and physical, arise and exist due to the presence of certain conditions, and cease once their conditions are removed: nothing except Nirvana is independant.

This is one of the ideas given against the idea of permanent, true self, or soul or Hindu Atman. Nothing is permanent, except Nirvana (and, in my view, God) and everything is impermanent and in constant flux.

Now you may be familiar with Yoda's quote, “Fear is the path to the dark side. Fear leads to anger. Anger leads to hate. Hate leads to suffering.” This is a basic Buddhist conditional linking. For Conditioned Arising, the abstract doctrine is standardly represented in a chain of twelve links, mapping the way towards suffering, or dukkha:

(1) Spiritual Ignorance --> (2) Constructing activities --> (3) (discriminative) consciousness --> (4) mind-and-body --> (5) the six sense-bases --> (6) sensory stimulation --> (7) feeling --> (8) craving --> (9) grasping --> (10) existence --> (11) birth --> (12) ageing, death, sorrow, lamentation, pain, grief and despair.

Here, through this map of Conditions Arising, we can see that suffering is initially caused by spiritual ignorance. 'Spiritual ignorance' is a phrase oft misunderstood. It does mean to actively ignore, it means to be unaware of spiritual truth, of the ultimate, true reality, to be bound to the illusionary world. This is spiritual ignorance.

Having mapped out the road to suffering, we then instantly know the road to true happiness and Nirvana, don't we? You flip the map the other way. Thus eventually fully realising and experiencing the true nature of reality (or, can be put another way, becoming with God, the true reality) is to become truly, and blissfully happy.

By all means, let me know if you have any questions about this is its quite an abstract concept.

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