Buddhism has developed into many forms with many teachings. However a close look at the suttas of the Pali Canon reveals the essential teachings of the Buddha.

Dukkha is the problem. (First Noble Truth) The Buddha was not interested cosmology or describing how the universe works. He wasn't interested in promulgating a philosophy. He saw clearly that the existential problems of aging, sickness and death had the same "tone" as pain, sorrow, grief & despair, as not getting what one wants and getting what one doesn't want - dukkha. He saw that in order to have a happy life, a truly fulfilling life, dukkha has to be dealt with. This was his quest when he left his home in the foothills of the Himalayas and headed south towards the Ganges plain. Very importantly, the Buddha also understood that dukkha isn't something "out there" - rather, it is an experience in the mind. He recognized that it was not possible to prevent the "out there" things like aging, sickness and death; that the only hope lay in controlling ones reaction to these unpleasant events.

The Buddha sought and found a "necessary condition" for the arising of dukkha - craving (tanha). (Second Noble Truth) The essence of Dependent Origination is "this that conditionality": "Dependent on this, that arises."

"If this doesn't occur, that doesn't arise." The Buddha wasn't interested in any ultimate reason why dukkha occurs; he wasn't interested in any sort of "complete explanation" as to why dukkha occurs. He was looking for an opening into which he could drive a wedge and thereby prevent dukkha. He sought to find something that was necessary in order for dukkha to arise. If he could find such a "necessary condition", this could provide him the lever needed to prevent dukkha from arising - prevent the necessary condition and dukkha is prevented. This was a fairly radical departure from the spiritual teachings of his day. Both the mainstream and fringe spiritual teachings 2500 years ago looked to "ultimate causes" - e.g. the gods, chance, fate, etc. The Buddha ignored ultimate causes and sought simply a "necessary condition"; something far less grandeous, much simpler, less explanatory, simply something completely practical. And he found a necessary condition that was capable of being worked with - craving (tanha). Craving isn't the only necessary condition for the arising of dukkha - others include being alive, being conscious, being thwarted. But these other necessary conditions were not workable - dying or being unconscious certainly are not useful ways of preventing dukkha, and life simply won't always unfold the way we want it to. So the Buddha had to work with craving. Notice that craving, like dukkha, is in the mind. This is another brilliant move on the part of the Buddha - it's a whole lot easier to reprogram your software than to rebuild the hardware of the universe.

The Buddha discovered how to prevent craving from arising - and thereby prevent dukkha from arising. (Third Noble Truth) Seeking a "necessary condition" for the arising of craving, the Buddha discovered that craving arises from vedana. But vedana - our pleasant, unpleasant, neutral initial reactions to sensory input are inevitable. Vedana arise from sense contacts which arise from the 6 senses that are part of having a conscious mind and body. So now the Buddha shifted to a new strategy - disenchantment (nibbida).