Heaven, Human, and Earth are based from IChing or the book of Change. So, this concept is of Chinese origin. not Buddhist.
Heaven, Huaman, and Earth is a symbol/concept where it can be used in fortune telling to stratergy…within person and environmental view… many many self-interpretation and usage. However, there is one concept, The concept of Heaven and Human is an unity is which means in western term "BE ONE with Nature " oftern brought up when dealing with ART.
In chinese martial art such as art from Fujian, Heaven, Human, and earth can means upper body, middle, and lower body technics, or potential/power, movementum, and shape…ect
And, the Localization Evolution of such as japanese Karate from the White CRane of Fujian carry the Upper, middle, lower body technics or Heaven, human, earth DNA.
Female martial art of China before 1850 has a big part of earth or lower body technics. Why? because, Chinese Female in the Ming Dynasty and big part of Qing era are subjected to a in-human custom of bound feet or footbiding. the famed writer and scholar Zhu Xi (1130-1200 A.D.). was aided in the spread of footbinding.
http://academic.brooklyn.cuny.edu/core9/phalsall/studpages/vento.html
With the “small and narrow” feet limitation, female of ancient china were subject to easily to be tip off balance and fell relative to nature unbond leg. Thus, there are Ground style chinese martial arts were indeed develop due to the consequence of the footbinding. One still can see these type of style in Fujian.
The characteristics of Wing Chun is Short bridge Narrow stance. However,
In general, Wing Chun, after the 70’s Bruce Lee or the world kicking heat, has taken a turn to Ascent to Sky. were kick such as side kick, knee raising. wider stance… etc were added to a localize evolution. …
The question then raise is while this Localization Evolution of Wing Chun co evolve with the world’s martial art, what has left or ignore? what has grown and manifest? is this manifestation a balance one supporting the Short Bridge Narrow Stance? or it has change the direction subtlely left un notice.
In additional, there are Localization Evolution of the Theory of Wing Chun Kuen, or presentation of the so-called older or oldest theory of Wing Chun Kuen presented today. And again, the question is, does these theory support the short brige Narrow stance of the Wing Chun Kuen? how is it adress the bondfeet facts which some obvious in the 1850 but left un notice today because high feel shoe is an option where one can take off any instant one would like? or it has taken anther path?
((you want to make an experiment? go to any Wing Chun Kuen Article or books, replace the shoe of the female practioners with a pair of 3 inch spike high heel, http://www.sexyshoes.com/p9887.html
then ask yourself, does this stance balance? does it make sense to stand this way? or buy a pair of the spike high heel doing SLT, Doing CK, Doing BJ, Doing Chi SAu…(just dont broke your wife’s 
or let your wife saw you doing it :D) try it and see what do you find out? ) )
As a personal experience, for a while, I often tested the concept of BROkEN ARROW with friends, range from beginer to skill martial artists or Grandmaster. The result is always “why do you like to open up this way to being subject to take down”.
What my experiment about has two fold, 1, to prove BROKEN ARROW is a kiss of DEATH in a Narrow Stance Short bridge art unconditionally. 2, while at take down and fall from different senerio, what happen? what is the nature tell me? ---- Since, remember, the female of 1850 and beyond cannot avoid to fall… how are they in the past “BE ONE with the Nature?”
You watch Angelina’s movie “taking life”? Agent Angelina lay on the scene to collect data, to let the scene tell her, what is going on. instead of spining and thinking… observe what happen?
From the Narrow stance and the bondingfeet nature, in my understanding, Earth or Ground in Wing Chun Kuen which has a fame of to be " feminine art" has a different way to deal with the Earth of the Ground.
Just some drunken thoughts