Breaking the chain

The Buddha's teaching on how suffering arises in life, Paticca-Samuppada, has no obvious translation; it is often referred to as the “Chain of Dependent Origination.” which is an ungainly phrase at best. Regardless of its clunky title, it presents a profound, psychological theory of the mind as a causal environment (a realm of karma), and it lies at the core of the 2,500 year old dharma. There is nothing mystical about the Buddha’s theory, it is an intriguing and systemic series of observations, as rigorous as William James or Von Helmhotlz; as original for its time as the work of Freud, Wertheimer, Bowlby and Ainsworth. Rather than review this insight in its entirety, it is worthwhile to highlight the key mechanisms. For such an endeavor we'll review a simple, run of the mill event in daily life, and explore, from the perspective of Buddhist insight, how it can blossom into full blown mental agitation and affliction.

Road rage: beginning the chain of suffering
To supply our example, let's imagine ourselves in a line of slowly moving traffic leading to a toll booth, during which someone races past us,  illegally employing the road shoulder, then abruptly pulls in front of our vehicle, a shameless method of getting ahead of others by any means necessary. Such an event—or sensory experience referred to as phassa in the language of early buddhism, pali—will invariably lead to a physical ‘gut’ reaction. Our abdominal muscles may tighten, the chest may compress, the lower jaw might clamp shut or shoulders lock up. (This is an automatic reaction that arises before any conscious control or intervention is possible, as the amygdala is responsible for our immediate, 'gut' or ‘priming’ reactions; it receives incoming sensory information well in advance of the frontal lobe, which provides our thought-based interpretations.) 
Now, were this event an agreeable one, we might expect the 'gut' reaction, or feelings, to be positive and pleasurable (sukkha vedana in pali); but in this scenario we’d likely experience muscle contraction, tension, stress, in other words a negative response (dukkha vedana).
At this stage there’s nothing we can do about the experience. Directly following this sequence, however, our involuntary gut reactions give way to conscious reactions that may appear natural, but are by no means inevitable: we add craving (tanha) to the gut feelings. Where our gut reactions were virtually immediate, the reverberations are intentional, controllable dispositions: we mentally interpret this event, no matter how universal and commonplace, as unfair, evil, a disgrace. Why do we add mental interpretations to life's universal experiences?
1) It allows the mind to make some sense out of life’s randomness, to place events into recognizable patterns
2) To distract our attention from the underlying physical, stressful reactions, which we are powerless over, to thoughts which give the illusion of future protection: “Next time I won’t allow that to happen.”
And so a garden variety event becomes an outrage, a passion for life to be other than it is. (This disposition is not inevitable, it arises in the anterior cingulate cortex, where we interpret our emotional responses to life.)

Craving: A war with life as it is
So we witness an event (phassa), we add an physical reaction (vedana), after which the mind places an interpretation onto the experience: “I don’t like this; it’s unfair; things should be otherwise.” Such a mental assessment—this or that event is wrong and should go away—is known as craving (tanha). We set our course on resisting life’s inevitable, unpleasant encounters; craving is a kind of war with life as it is, a form of resistance and mental agitation that sustains and prolongs what might have been a fleeting perception of little duration. The belief that ‘life should be otherwise’ and ‘this is unfair’ are the rich soil from which a great deal of obsessional thought can grow. Once we enter the realm of thought based interpretations, the chain of suffering rapidly picks up momentum and becomes increasingly difficult to disentangle.

Clinging: A whole lot of thinking going on
Our disappointment turns into an ‘attachment’ (upadana) which manifests in a series of opinions and ideas about notable event:s long, internal diatribes and comments about the quality of driving these days, the unfairness of life, victimization stories and so on. In life, clinging or attachment doesn't necessarily require physical contact; most often its a continuation of thinking about an experience long after it has passed; and so we may find ourselves reliving the story of being cut off on the road hours later.
It's interesting to note that the word used for attachment, upadana, actually means to feed upon something; the Buddha taught, provocatively, that keeping something in the mind after the external event has passed, is a form of consuming our impressions of life, the mind feeing on memories and ideas (many sensations and ideas the mind feeds on are, unfortunately, essentially junk food). The mind, the Buddha informs us, likes to consume four types of mind food:
1) images, memories, impressions, etc of that which supplies us with sensory pleasure (beautiful people, places, things, pleasurable sensations and experiences, etc)
2) a wide variety of views and opinions about the world, life, people, etc
3) our ingrained habits, routines, rituals
4) the endlessly unfolding internal auto-biographies and random thoughts about ourselves that provide us with endless fascination

Becoming: Where suffering becomes a way of life
Caught in a spiral of attachment to a past event, worry or fantasy, over time we may even find ourselves evolving a new personality or identity (bhava); our view of who we are is changing; we become ‘the person who was cut off.'  We construct a divide between those of us who live life the right way—by staying in lane—and those people, who cheat to get ahead. This may sound ludicrous, but identity beliefs are founded on such bizarre, artificial segmentations: sports and music fans, political debates, film enthusiasts, it all boils down to 'us' and 'them.' Just as the idea of ‘left’ requires the concept of ‘right’ to give it meaning, and  ‘up’ implies a ‘down,’ ‘good’ brings with it ‘bad,’ and so on with life dualisms: in referring to distinctions we inadvertently create conflict; for any character or distinctiveness requires an opposition to attain its value. An ‘I’ cannot exist without a ‘You’ that is attributed with difference. What we affirm and believe in only exists via a relation to something that is disowned, suppressed, abolished; when we take on an identity belief, we move headlong into contention with those we deem to be ‘others.’
If the preceding seems abstract, bear in the mind that it is the underlying cause of all the world's conflict: in the great ‘Madhupindika Sutta (Ball of Honey Teaching)’ the Buddha elegantly draws a straight line between thinking that establishes self (papanca) and contention and strife:

“If we see that there is nothing to admire in the way we compulsively objectify and identify ourselves, then we can be free of our obsessive obsessive views and fears, even our ignorance. Then we can put aside our weapons, our running arguments, feuds and disputes with others, along with all our hateful speech.”

So the stories we tell about ourselves and those we deem ‘the same as us’ may seem innocent and fascinating, but they’re facades concealing obsessional, self-centered ideation (papanca). Rather than establishing self around positive attributes we commonly share with other beings, identity stories result in conflict, a war with life.

There is a way out
At this point we can conclude by noting that there is a way out of this cycle of frustration, a weak link in the chain as identified by early buddhism. While we are incapable of stopping the arising of gut reactions, or vedana, we can develop, over time and practice, the ability to experience our reactions without adding judgment or resistance. This practice is known as mindfulness (sati) and its effectivity cannot be overestimated, as it now provides the core tools of contemporary therapies such as Mindfulness Based Stress Reduction (MBSR), Mindfulness Based Cognitive Therapy (MBCT), Dialectical Behavioral Therapy (DBT) and on.

When our feelings arise in the body and breath, we interrupt the process of adding outrage and opinions, and proceed instead to maintain attention to the physical reactions, allowing them to arise and pass without resistance, containment, interpretation and so on. In putting aside the stories we tell about life, we open to true, lived experience in and of itself; rather than suppressing our feelings, we give them space and the attention they need. In this way we break the chain of suffering and the war with life as it is.