This is probably where the practice of directing metta to specific people came from
Pervading The Divine Abiding – MN7 (excerpt) wrote:Mettā-sahagatena cetasā ekaṃ disaṃ pharitvā viharati Tathā dutiyaṃ tathā tatiyaṃ tathā catutthaṃ Iti uddhamadho tiriyaṃ sabbadhi sabbattatāya Sabbavantaṃ lokaṃ mettā-sahagatena cetasā Vipulena mahaggatena appamāṇena averena abyāpajjhena pharitvā vihāratī
I will abide pervading one direction with a mind endowed with friendliness; in the same way the second, in the same way the third, in the same way the fourth; thus above, below, around and everywhere, extended to all; renouncing the entire world with a mind endowed with friendliness; dwelling suffused with this abundant, lofty, & limitless state that is without aggression, or ill-will.
mixed with this
[quote=""Sigalovada Sutta: The Discourse to Sigala" (DN 31), translated from the Pali by Narada Thera. Access to Insight, 24 March 2012,
http://www.accesstoinsight.org/tipitaka ... .nara.html" onclick="window.open(this.href);return false; . Retrieved on 9 September 2012."]"And how, young householder, does a noble disciple cover the six quarters?
"The following should be looked upon as the six quarters. The parents should be looked upon as the East, teachers as the South, wife and children as the West, friends and associates as the North, servants and employees as the Nadir, ascetics and brahmans as the Zenith.[/quote]
this does support the idea that metta isn't a formal practice done like anapana, but the formal practice is also useful!
Blog, Suttas, Aj Chah, Facebook.
He who knows only his own side of the case knows little of that. His reasons may be good, and no one may have been able to refute them.
But if he is equally unable to refute the reasons on the opposite side, if he does not so much as know what they are, he has no ground for preferring either opinion …
...
He must be able to hear them from persons who actually believe them … he must know them in their most plausible and persuasive form.
John Stuart Mill