Bhante Gunaratana discusses the following topics: the unconditional nature of metta, sending metta to others, Bhrama, cultivating and perfecting the brahma viharas using a balanced approach with metta, the type of metta offered by the Buddha, the five spiritual faculties, and the five spiritual strengths. 

The full text of the Discourse on Loving Friendliness:

One skilled in good, wishing to attain
That state of peace, should act thus:
One should be able, straight, upright,
Obedient, gentle and humble.

One should be content, easy to support,
With few duties, living lightly,
Controlled in senses, discreet,
Not impudent, unattached to families.

One should not do any slight wrong
Which the wise might censure.
May all beings be happy and secure!
May all beings have happy minds!

Whatever living beings there may be
Without exception: weak or strong;
Long, large, medium, short;
Subtle or gross;

Visible or invisible;
Living near or far;
Born or coming to birth
May all beings have happy minds!

Let no one deceive another
Nor despise anyone anywhere
Neither from anger nor ill-will
Should anyone wish harm to another.

As a mother would risk her own life
To protect her only child,
Even so towards all living beings
One should cultivate a boundless heart

One should cultivate for all the world
A heart of boundless loving friendliness,
Above, below, and all around,
Unobstructed, without hatred or resentment.

Whether standing, walking or sitting,
Lying down or whenever awake,
One should develop this mindfulness.
This is called divinely dwelling here.

Not falling into erroneous views
But virtuous and endowed with vision,
Removing desire for sensual pleasures,
One comes never again to birth in the womb.