Any ideas for what the MND stat represents?

[Enkidoh]

Well, remembering how it was sort-of described in FFXI, 'mind' appears to be basically belief in a higher power (in FFXI's case - the goddess Altana), all 'holy' type spells, along with cure magic, used MND as it's guiding stat, and hence the elvaan (FFXI's equivalent of elezen), where stated as being very devout (in fact they were the most religious race) - no surprises they had the highest native MND stat of the five races and hence made excellent healers.

On the other hand, intelligence was basically exactly what it says on the tin, not so much a belief in the supernatural (ala, a god's divine providence), but rather material knowledge and curiosity - naturally because the elvaan were regarded as being very arrogant, pigheaded and 'closed minded', their intellect naturally was low - this also explained why the elvaan city of San d'Oria was a backward, medieval castle with a stagnating, decadent society.

Compared to the elvaan, the tarutaru (FFXI's equivalent to lalafell), having the highest INT stat in the game, were literally stated as being the most intelligent of the five races. They're a naturally curious race, and were the original discoverers of magic. Despite this, much of the taru's home nation of Windurst wasn't just given over to study of the occult, but science in general and even limited technology, like astronomy and bioengineering (for instance, they created bio-luminescent 'fluroflora' which was used as a form of lighting in Windurst).

Hence, I'm pretty sure the two stats lore wise have similar ideas here in FFXIV as well, although given the fact racial stat differences in FFXIV are less pronounced as they are in FFXI, it naturally doesn't seem to extend into Eorzean society in general as well.