I have come across an essay ,written by a certain bhikkhu,which might be of interest, it is part of a larger piece but this section seems most relevant for this discussion:
"An enlarged mind vs. An unenlarged mind
The term mahaggata is generally used to refer to a mind that has somehow grown, expanded, become larger, but what this actually means is far from self-evident. One place that we often meet the term is in the stock expression that describes the cultivation of the brahmavihÄrÄ , such as here in MN 7.
so mettÄsahagatena cetasÄ ekaį¹ disaį¹ pharitvÄ viharati, tathÄ dutiyaį¹, tathÄ tatiyaį¹, tathÄ catutthaį¹. iti uddhamadho tiriyaį¹ sabbadhi sabbattatÄya sabbÄvantaį¹ lokaį¹ mettÄsahagatena cetasÄ vipulena mahaggatena appamÄį¹ena averena abyÄpajjena pharitvÄ viharati; karuį¹Äsahagatena cetasÄā¦peā¦. muditÄsahagatena cetasÄā¦peā¦. upekkhÄsahagatena cetasÄ ekaį¹ disaį¹ pharitvÄ viharati, tathÄ dutiyaį¹, tathÄ tatiyaį¹, tathÄ catutthaį¹. iti uddhamadho tiriyaį¹ sabbadhi sabbattatÄya sabbÄvantaį¹ lokaį¹ upekkhÄsahagatena cetasÄ vipulena mahaggatena appamÄį¹ena averena abyÄpajjena pharitvÄ viharati.
He dwells having pervaded one direction with a mind endowed with loving-kindness; likewise the second; likewise the third; likewise the fourth. Thus he dwells having pervaded up-&-down, horizontally, spread out over the entire world with a mind that is endowed with loving-kindness, large, enlarged, unbounded, immeasurable, without anger, without ill-will. He dwells having pervaded one direction with a mind endowed with compassion ā¦ sympathetic joy ā¦ equanimity; likewise the second; likewise the third; likewise the fourth. Thus he dwells having pervaded up-&-down, horizontally, spread out over the entire world with a mind that is endowed with equanimity, large, enlarged, unbounded, immeasurable, without anger, without ill-will.
MN 7
Cultivating mettÄ means pervading the mind with the intention of good-will for all beings. The phenomenon of āpersonā (which arises for the puthujjana , and includes āthis-person-who-I-amā) and the phenomenon of āindividualā are simply phenomena which arise. They arise against a background which is the mind, and this will have certain underlying or latent tendencies (unless one is an arahat ) which pull the experience in certain directions. For instance, as we have seen, a mind infected with paį¹ighÄnusaya (the underlying tendency to ill-will) will be affected by the arisen phenomena and will tend towards an aversive response. One is more likely to perceive the unpleasant and to be repelled. One who cultivates mettÄ works at changing the underlying tendencies. By pervading the background (i.e. the mind) with a sense of acceptance, benevolence, amity, whenever the phenomenon of other people (or the phenomenon of this person) arises, this will be manifested on a background of mettÄ . The tendency will be to respond to people on the basis of this quality of mettÄ .
The Buddha encouraged his disciples to develop a mind endowed with loving-kindness ( mettÄsahagata citta ), but it is important to understand that one cannot do this without first knowing what the mind is. It is only once one has discerned what citta is, once one has grasped the nimitta of citta, that it becomes possible to endow it with certain qualities such as loving-kindness, compassion, or simply to brighten or gladden it. How could it be possible for one to gladden the mind without knowing what the mind is? It is perhaps worth noting here that this also applies to ÄnÄpÄnassati . Before one can develop mindfulness of in-&-out breathing, one first needs to have discerned the phenomenon of mind.
ācittapaį¹isaį¹vedÄ« assasissÄmÄ«āti sikkhati, ācittapaį¹isaį¹vedÄ« passasissÄmÄ«āti sikkhati; āabhippamodayaį¹ cittaį¹ assasissÄmÄ«āti sikkhati, āabhippamodayaį¹ cittaį¹ passasissÄmÄ«āti sikkhati; āsamÄdahaį¹ cittaį¹ assasissÄmÄ«āti sikkhati, āsamÄdahaį¹ cittaį¹ passasissÄmÄ«āti sikkhati; āvimocayaį¹ cittaį¹ assasissÄmÄ«āti sikkhati, āvimocayaį¹ cittaį¹ passasissÄmÄ«āti sikkhati.
One trains thus: āI will breathe in as one who experiences the mindā. One trains thus: āI will breathe out as one who experiences the mindā. One trains thus: āI will breathe in having gladdened the mindā. One trains thus: āI will breathe out having gladdened the mindā. One trains thus: āI will breathe in having composed the mindā. One trains thus: āI will breathe out having composed the mindā. One trains thus: āI will breathe in having liberated the mindā. One trains thus: āI will breathe out having liberated the mindā.
MN 118
When the quality of mettÄ is fully established one knows that any being that one might encounterāany being at allācan only be encountered within this field of mettÄ . One now knows that it is not possible to experience any being (whether, in the case of the puthujjana , my self or others, or whether, in the case of the arahat , this individual set of the five aggregates or five aggregates externally) without them being there within this context of good-will. The mettÄ is now all-pervasive, unbounded, infinite. It is in this way that the mind can be reckoned in terms of its size and can be described as vipula (large, extensive, abundant), mahaggata (enlarged, expanded, become great) or even appamÄį¹a (immeasurable, unbounded, unlimited, infinite). When one has discerned the mind, and knows that the mind is always the larger background within which more particular phenomena arise, then one knows that whatever particular thing I attend to, the mind is always bigger than that. In this sense, the infinity of the mind can be known. That is why the arahat , one who has fully understood the mind, can be described as one with an immeasurable mind."