The first section on the Sutra on the Four Establishments of Mindfulness reads:

I heard these words of the Buddha one time when he was living at Kammassadhamma, a market town of the Kuru people. The Buddha addressed the bhikkhus, “O bhikkhus.”

And the bhikkhus replied, “Venerable Lord.”

The Buddha said, “Bhikkhus, there is a most wonderful way to help living beings realize purification, overcome directly grief and sorrow, end pain and anxiety, travel the right path, and realize nirvana. This way is the Four Establishments of Mindfulness.  What are the Four Establishments?

1) Bhikkhus, a practitioner remains established in the observation of the body in the body, diligent, with clear understanding, mindful, having abandoned every craving and every distaste for this life.

2) He remains established in the observation of the feelings in the feelings, diligent, with clear understanding, mindful, having abandoned every craving and every distaste for this life.

3) He remains established in the observation of the mind in the mind, diligent, with clear understanding, mindful, having abandoned every craving and every distaste for this life.

4) He remains established in the observation of the objects of mind in the objects of mind, diligent, with clear understanding, mindful, having abandoned every craving and very distaste for this life.”

When I hear the words, “The Buddha said, Bhikkhus, there is a most wonderful way to help living beings realize purification, overcome directly grief and sorrow, end pain and anxiety, travel the right path, and realize nirvana. This way is the Four Establishments of Mindfulness,” a great sense of relief, ease and confidence emerges. The Buddha is saying that this path toward the end of suffering is available to everyone; it is not complicated. We do not need to have some profound intellectual capacity, or have some particular cultural disposition or have a specific genetic structure to accomplish this. It is available to all of us through essentially the incredibly simple practice of mindfulness.

Scholars tell us that of all of the Buddha’s teachings that we have in written form, the Sutra on the Four Foundations of Mindfulness may well be among the oldest and most authentic and closest to what the Buddha actually said. If we are to believe that the Buddha actually accomplished the end of all suffering, pain and anxiety while living in this world then I think we can believe that this is the most basic way that he taught others to accomplish that same thing. And at the same time, as the sutra says, we will be helping all other living beings to accomplish the end of their suffering as well. So we can feel a great sense of relief and joy. We have found a path that leads us as individuals into peace and harmony with this world we live in and it has nothing to do with being selfish. The longing we have to be free is the same as all other beings, and as we gradually liberate ourselves from our own restrictive karmic formations, we also help to liberate others beings simultaneously. The diligent practice of Mindfulness of the Body, Feelings, Mind and Objects of Mind is the direct way of accomplishing this.

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Quote from:
“Transformation and Healing, Sutra on the Four Establishments of Mindfulness,” translated from the Satipatthana Sutta from the Majjhima Nikaya, number 10, from the Pali by Thich Nhat Hanh and Annabel Laity.