Part 2 - Meditation on kindness

a. Increasing kindness As explained above:

After the mind has developed this equanimity,
Think of the happiness that you want for your mother.
Then contemplate all embodied beings in just that way.

When the mind has been equalized, just as we are kind and pleasant towards our fathers and mothers, meditate on all sentient beings, placing the mind in the attitude we have toward our parents. So meditate on kindness. The Prajñaparamita in Eight Thousand lines says:

Meditate with an attitude of kindness, not letting it be ravished away by all the shravakas and pratyekabuddhas.

b. The object of kindness

How is this done?:

Kindness has the object of all sentient beings.
It hopes that they may encounter, in the incidental aspect,
The happiness that pertains to gods and human beings,
And, ultimately, the happiness of enlightenment. 
Meditate, going from thinking of a single being
Up to all beings, as far as the limits of the directions.

When unhappy sentient beings are seen, think, “May they meet incidentally with the happiness of gods and humans, and ultimately with the happiness of buddhahood.” Thinking that, go from one to meditating on all sentient beings, as limitless as the space of the sky. The Middle Length Prajñaparamita says:

When we see sentient beings who have no happiness, we should think, “May these sentient beings attain the god realm, where the happiness of the gods is perfect.”

c. The sign of training in kindness

As for training:

The sign of success is supreme and all-pervading kindness.
Greater than a mother’s love for her only child.

Whatever sentient beings are seen, we are pleased, and, with a great kind longing, we want to help them.

d. Kindness without object

After meditating on kindness with an object:

Then rest everything in equanimity.
This is the great kindness without any reference point.
The sign is the unity of kindness and emptiness.

The object of meditation on kindness is sentient beings, who arise from the gathering together of the six elements. These elements are

1. earth
2. water
3. fire
4. air
5. space
6. consciousness.

If these elements are examined, their coarse atoms, subtle real nature, and consciousnesses of all this do not exist as real things.  Meditate, thinking that they are like space.  The Precious Garland says:

People are not earth and are not water.
Neither are they fire, air, nor space,
Nor are they consciousness, nor all of these.
A person is something different from these.

Since persons are gathered from the six elements,
They are not real, and in a similar way,
Any nature gathered from each of the elements
likewise cannot be something that is real.

The skandhas are not the ego, nor ego the skandhas.
Yet neither would be there without the other.

Also:

At the time when no things can be found,
At that time there is pure thinglessness.

Things of form are simply non-existent,
Even space is nothing but a name.
With no arising, form is superfluous.
Therefore, even its name does not exist.

Feelings, perceptions, and conditioned formations,
As well as consciousness, just seem to rise,
Regarded in thought as if they were a self.
Thus, the six elements are selflessness.

Why does no self exist? When sentient beings appear, if we examine their bodily nature, it does not exist. Neither a support or supported of consciousness is seen, so no “me” and “mine” are perceived. When analyzed, they vanish, essentially empty. The same text says:

Just as if the layers of a plantain tree^[1]
Are all destroyed, then nothing is there at all;
People too, if all the parts of their nature
Should be destroyed, would likewise disappear.

Because all dharmas are without a self,
That is what the victorious ones have taught.

This mere appearance of seeing and hearing is neither true nor false, since truth and falsity are just patterns of dharmas in the mind. The same text says:

Our just being able to see and hear and so forth,
Is taught as being neither true nor false.

Also it says there:

This world transcends both truth and falsity.

Thus all dharmas are beyond truth and falsity, like a plantain or banana tree.  This is also taught in the King of Concentrations Sutra:

Just as with the herbaceous trunks of plantain trees,
Wanting to find their real substance, people tear them up,
But nowhere inside or out is that substance to be found;
All the various dharmas should be known like that.

The sign of good training is that while kindness arises, at the same time there arises the realization that sentient beings, like a plantain tree, essentially have no self or nature.

e. The fruition of meditating on kindness

What is the fruition?:

The visible result is experience of pure pleasure.

Seeing  sentient  beings  is  pleasurable,  and  the beings, when they are seen, are cleansed of disturbances of love and hate and so forth. The Prajñaparamita in Eight Thousand Lines says:

Those who have an attitude of kindness meditate a great deal, and when they see the sentient beings inhabiting the world, it is pleasurable. They have no anger.

Also immeasurable merit is attained.  The Sutra of the Great Liberation Blossoming in the Ten Directions (thar pa chen po phyogs bcu rgys pa’i mdo) says:

Though someone in the world
May keep pure discipline
For even as long as a kalpa,
An instant of joy in one person
Produced by kindness is better.

In the world, whoever does evil
In body, speech or mind,
Surely falls to the three lower realms;
But kindness will instantly cleanse it.

Footnotes and references:

[1]:

An onion is good western equivalent.