The first of the Four Noble Truths is the Truth of Suffering. This means that all things in this world cause suffering if we do not listen to or if we forget the Buddha's teachings. In other words, “Pain is inevitable, suffering is optional.” To acknowledge the real condition of pain or suffering and see it through - without avoiding it or meeting it only halfway, is the Truth of Suffering.
The Truth of the Cause of Suffering means that we must reflect on what causes and conditions have led us to suffer, and then we can deeply investigate them to understand them clearly. The investigation of the cause of suffering is shown in the doctrines of the “Reality of All Existence” (Ten Suchnesses) and the Twelve Causes and Conditions. The original cause of all suffering is “ignorance” as seen in the Twelve Causes and Conditions.
The Truth of Extinguishment of Suffering is the state of absolute quietude we experience when our human sufferings have been extinguished. This state is attained when we awaken to the three Universal Truths: “All things are transient, ” All things are nonself, ” and “Nirvana is tranquility.” These three truths, called the The Three Seals of the Dharma, are so important that they form the three fundamental principles of Buddhism. When we recognize and let go of sufferings caused by physical, mental, or emotional attachments, we are then able to recognize this physical world as the Land of Eternally Tranquil Light (referred to in the Sutra of the Method of Contemplating the Bodhisattva Universal Sage as the land of the Buddha Vairocana).
The Truth of the Way that Extinguishes Suffering is that by practicing the teachings in our daily lives we will realize these great Truths. We follow the Bodhisattva Way with our minds, words, and actions by practicing the Eightfold Noble Path and the Six Perfections. The truth of the way shows the way to a dynamic state of harmony and balance, of absolute peace and quietude, which is attained by practicing these teachings. The Law of the Four Noble Truths teaches us to acknowledge and face the reality of human pain and suffering, the Truth of Suffering; to grasp its real source, the Truth of the Cause of Suffering; to know there is a way to extinguish suffering, the Truth of Extinguishment of Suffering; to practice the Bodhisattva Path daily to remove the suffering, the Truth of the Way that Extinguishes Suffering.
The Buddha said: “One thing only do I teach: suffering and the cessation of suffering.”