“Bhikkhus, it is through not realizing, through not penetrating the Four Noble Truths that this long course of birth and death has been passed through and undergone by me as well as by you. What are these four? They are the noble truth of dukkha; the noble truth of the origin of dukkha; the noble truth of the cessation of dukkha; and the noble truth of the way to the cessation of dukkha. But now, bhikkhus, that these have been realized and penetrated, cut off is the craving for existence, destroyed is that which leads to renewed becoming, and there is no fresh becoming.”
Maha-Paranibbana Sutta: The Last Days of the Buddha, trans. Sister Vajira, Mr. Francis Story, http://www.accesstoinsight.org/ptf/dhamma/sacca/
After achieving enlightenment, the Buddha went through a period of thinking that no one else would be able to understand what he had just realized. As he thought about it, though, he recalled that some of his former companions were very close to his level of realization and would require relatively little instruction to catch up to him, so he sought them out. His first teaching consisted of the Four Noble Truths, which one can summarize briefly as life is suffering, or disappointment (the word “dukkha” above is the original word the Buddha used), the source of disappointment is craving, or attachment to desire, an end to suffering is possible, and the route to the end of suffering is the Noble Eightfold Path.
That’s it. Now you know all there is to know.
Of course, one can, and people have, expound at great length on this simple teaching, and actually treading the Noble Eightfold Path can take a lifetime. The Dalai Lama has said that his litmus test for whether a given individual or group is really Buddhist or not is whether they understand and appreciate the Four Noble Truths, so you’re already halfway there.
As a beginning, many people might be inclined to think that they’re not suffering. Indeed, I hope you’re not. The Pali term is “dukkha,” which, like most words, can be translated in multiple ways. One other synonym is disappointing. And Buddhists use even this term in a very specific way. Think of your absolute all time favorite activity, your favorite food to eat, your favorite vacation, your favorite sexual event. No matter how much you enjoy it, you know it will only last a certain amount of time. It simply is not possible to engage in your favorite activity all of the time. Even if you move to your favorite vacation spot, then you’ll have a house to keep up or an apartment to clean, and you have to sleep some time. So life has a substantial component of disappointment built into it. This is unavoidable.
You may have heard the old saying that pain is inevitable, but suffering is optional. From the Buddhist perspective, what that means is that the disappointment of having pleasurable experiences end, and of having unpleasant experiences occur despite your best efforts to prevent them, are unavoidable characteristics of human existence. What we can avoid is wishing this were not so. Suffering is not inherent in pain. Suffering is the result of your reaction to the pain. It may seem inevitable to wish for pleasure to continue forever and for displeasure to stay away always, but those are choices we make. Even without meditating at all, anyone can choose to realize these unavoidable features of human life and accept them as such instead of trying to change what no one can change. Indeed, to some extent, we just call this growing up. Part of being a child is to grow hugely upset at the realization that the birthday party is over or there is no more cake. Adults just recognize this fact of life and don’t worry too much about it. Treading the Noble Eightfold Path to the cessation of suffering/disappointment is like just growing up more fully. To some extent, it really is that easy. You can choose not to try to change what no one can change and just accept it instead. The problem is that we all have deeply ingrained habits of wishing for the impossible and trying to achieve it that will haunt us until we get control over our minds. Much of Buddhism, if not all of Buddhism, is about exploring those habits and cultivating the means to overcome them.
So the Second and Third Noble Truths are closely linked. The source of our suffering is our clinging to wanting the world to be other than it is. Therefore, the way to end suffering is obvious. But, as is so often the case in human life, even when the path is clear, actually travelling it can be difficult. So the Buddha offered a guide, a map of sorts, to get you from wherever you are now to where you want to be: the end of all suffering. That is the Fourth Noble Truth: that the path to the end of suffering is the Noble Eightfold Path.