There are 4 foundations of mindfulness. It means that there are 4 kinds of objects of looking deeply. To meditate means to have a time to practice looking deeply. And looking deeply of what? What is the object of mindfulness? What is the object of concentration? And what is the object of your mind?
And we know very well that the first realm, object of meditation is "body". And there is a sutra, scriptures on the contemplation of the body in the body. In fact, there are many. But there is one with the title, "The Contemplation of the Body in the Body". So, the body is the first object of meditation. You have to meditate on your body. You look deeply into your body.
(1. be with I+O)
And in "The Sutra on Mindful Breathing", you have these 4 exercises in order to handle your body. And the first is to be with your in-breath and with your out-breath. You approach your body first by contacting your in-breath and out-breath. The best way in order to approach your body is through the way of in-breath and out-breath. With mindful breathing in and out, you connect yourself with your body. And the practice is pleasant also.
(2. follow I+O)
The second exercise is to follow your in-breath and out-breath all the way through. In that way, you increase your mindfulness and your concentration. And that is also pleasant. Just to sit and enjoy breathing in and follow your in-breath from the beginning to the end can bring a lot of joy and of healing.
(3. aware of body)
And the third is to be aware of your body, to be with your body. Connecting with your body, remember that you have a body. Bring your mind home to your body in order for you to be established in the here and the now, for you to have a chance to live your life. And you have an opportunity to live each moment of your life deeply. You are not pulled away by the thinking about the past, by the thinking about the future and so on. And all these exercises are very simple but effect is enormous. Because if you are in touch with your body, you are in touch with life, the cosmos and the planet earth.
(4. calm body)
And the fourth exercise as we already know, that is to release the tension in your body to calm your body. And there are more instructions given by the Buddha so that we can look deeply into our body and restore wellness in our body. And there is an exercise proposed by the Buddha. He used the example of a farmer going up to a seller and bringing down a bag of seeds. And he opened one side, one end of the bag and allowed all kinds of seeds to flow on the floor. And with eyes still in good condition, he recognized every sort of seeds. And he recognized, "This is a mung bean seed. This is a kidney bean seed. This is a corn seed. And so on."
So, the same thing is true with the practitioner. In the lying position or the sitting position, the practitioner practices in review of all elements in his body, beginning with his head and down. Breathing in, I'm aware of my brain. Breathing out, I smile to my brain. Breathing in, I'm aware of my eyes. Breathing out, I smile to my eyes. And you go down, you go down. Breathing in, I'm aware of my heart. Breathing out, I smile to my heart. You practice in review of all parts of your body like that farmer. He recognized every kind of seeds that is seen on the floor. So, this is the scanning of your body, not with the x-ray but with the ray of mindfulness. You recognize every part of your body and you smile to it. And you may find that they are conditions of your happiness.
And whenever you go through the part of your body that is not well, you may like to stay with that longer. And breathing in and out, send your compassion and embrace the part of your body with compassion. Suppose you have some troubles with your leber. And while scanning your body with mindfulness, you come to your leber and you know that your leber needs more of your attention, your mindfulness, your compassion. So, you should stay longer with your leber. Breathing in, become aware of your leber. And in situation of breathing out, embracing your leber with the energy of mindfulness and compassion, that helps you even if you are taking some medicines. This will help the healing to happen more quickly. So, looking into your body and helping your body to suffer less and to restore its well-being, and that is the first object of meditation, the contemplation of the body in the body.
I understand that "the body in the body" means "Dharma body in the physical body" in the phenomenal world. And I also understand that Dharma body (who is breathing) means awareness, non-separate self, true self, the whole cosmos, cosmic body, or the Buddha.
So, I understand that Thay's phrase of "Bring your mind home to your body" means "Bring your thinking in the past or the future back to Dharma body (awareness) in the here and the now". But I feel that the expression of "Bring your mind home to your body" is strange because mind (thinking in the past or the future) can't return to the present moment. Therefore, I feel the expression of "Transform your mind from thinking to awareness" or "Transform yourself from ego to awareness" or "Revive awareness" is easier to understand.
Thay explained that the scanning of the whole body (every organ) from head to toe with the ray of mindfulness is the contemplation of the body in the body. It may be so (especially in the third and the fourth exercises). But I feel (especially in the first two exercises) that the contemplation of the body in the body may mean to revive Dharma body (awareness) through mindful breathing, or conscious breathing. That's because breathing is the action by awareness (non-separate self). (Breathing is not the action by ego, or separate self.)
Thích Nhất Hạnh