The Four Noble Truths
More simply put, suffering exists; it has a cause; it has an end; and it has a cause to bring about its end. The notion of suffering is not intended to convey a negative world view, but rather, a pragmatic perspective that deals with the world as it is, and attempts to rectify it. The concept of pleasure is not denied, but acknowledged as fleeting. Pursuit of pleasure can only continue what is ultimately an unquenchable thirst. The same logic belies an understanding of happiness. In the end, only aging, sickness, and death are certain and unavoidable.
The Four Noble Truths are a contingency plan for dealing with the suffering humanity faces — suffering of a physical kind, or of a mental nature.