The Blessed Buddha once explained:
How is the release of mind by infinite mutual joy (Muditā) achieved?
What does this liberation have as its destination, what is its culmination,
what is its sweet fruit, and what is the ultimate goal of mental release
by universally mutual, unselfish, altruistic, appreciative & rejoicing joy?
Here, Bhikkhus, a Bhikkhu dwells pervading the frontal quadrant with a
mind imbued with infinite mutual joy, so the 2nd, 3rd and 4th quadrant.
As above, so below, across, and everywhere to all beings as for himself,
he dwells pervading the entire cosmos with a mind fully saturated with
unlimited mutual joy, immense, exalted, measureless, without hostility,
without any enmity, without any trace of ill will, of jealousy or of envy!
Thus prepared and mentally quite expanded, he then develops:
1: The Awareness Link to Awakening joined with limitless mutual joy.
2: The Investigation Link to Awakening fused with such mutual joy.
3: The Energy Link to Awakening together with infinite mutual joy.
4: The Joy Link to Awakening accompanied with absolute mutual joy.
5: The Tranquillity Link to Awakening linked with noble mutual joy.
6: The Concentration Link to Awakening associated with mutual joy.
7: The Equanimity Link to Awakening joined with endless mutual joy.
Based upon seclusion, disillusion, ceasing, and culminating in release...
If he then wishes:
May I dwell experiencing repulsion by any attractive & tempting object,
then he can dwell experiencing repulsiveness therein. If he wishes: May I
dwell experiencing the unrepulsive in any disgusting and repulsive object,
then he experiences pleasing beauty in whatever disgusting & ugly thing!
If he wishes: Avoiding both the repulsive & the unrepulsive, may I dwell
in equanimity, just aware & clearly comprehending, then he experiences
equanimity, just aware and clearly comprehending! When meditating he
can completely transcend the realm of infinitude of space, only aware
that consciousness is infinite, he can enter and dwell in the sphere of the
infinitude of consciousness.. I tell you Bhikkhus for a quite wise Bhikkhu
here, who has not yet penetrated to an even more superior mental release,
the mental release by infinite, altruistic and mutual joy has the sphere of
the infinitude of consciousness as its culmination!
Comments: Are you Discontent? Here is Why!
Mutual joy is the proximate cause of contentment.
Consequentially: Lack of mutual joy produces frustrated discontent!
Mutual joy also eliminates jealousy and envy! Absence of mutual joy
therefore induces the acid like mental pain called envy and jealousy!
Source of reference (edited extract):
The Grouped Sayings of the Buddha. Samyutta Nikāya.
Book [V: 115-21] 46: The Links. 54: Joined by Friendliness...