2g) How a newly born joy is produced in these

By ultimate bodhicitta:

This possesses the essence of the wishing tree of compassion.
As for its bearing well the heavy burden of beings,
In this world even the gods, like Brahma and the others,
Even for themselves, have never dreamed of this,
Let alone seeking this bodhicitta for other beings;
So this creates a joy that has never existed before.

Entering the Middle way (Madhyamakavatara, dbu ma la ‘jug pa) says:

Pratyekabuddhas and shravakas are born from the Lords of Sages.
As for those buddhas, they are born from the bodhisattvas.
It is the mind non-dual with the mind of compassion,
Bodhicitta, which is the cause of those buddha children....
Therefore, first of all, compassion should be praised.

In that way, the wishing tree of compassion bears the burden of the flock of birds of limitless sentient beings. As for that ultimate bodhicitta, those wishing benefit just for themselves and for their fathers mothers and so forth are without it. Even lords of the world like Brahma and so forth are without this, even for themselves. Up to now they have cared only for this life. Such an attitude, previously unborn, should be rejoiced in.

That is what is being said. The Bodhicharyavatara says:

Even if we include the love of fathers and mothers
Who has such a attitude of benefit?
Do even those who are gods and highly accomplished sages
Or does even Brahma have anything like this?

If, before now, none at all of these sentient beings
Had such an attitude, even for their own benefit,
If it was not dreamed of, even in a dream,
How did such benefits ever rise for other beings?

This wish to benefit by bringing joy to others,
Which does not arise for one’s own self as well,
This specially precious thought of benefiting beings,
Is a wonder which is born without precedent.

This wondrously arisen attitude accomplishes the benefit of both oneself and others. It is the supreme offering to the Tathagata. The same text says:

This itself is pleasing to the tathagatas..
This itself accomplishes our true benefit.
This itself removes the sufferings of the world.
Therefore this itself should always be done by me.

Instructing us to arouse bodhicitta, even if we do not attain buddhahood, the Bodhicitta Commentary (byang chub sems ‘grel) says:

As for bodhicitta, without producing it,
We will never attain the level of buddhahood.
Within samsara, for benefiting oneself and others,
No other skillful means exists but this alone.