There is no such thing as a "soul".
"Souls" don't exist.
However, there is an observable phenomenon called "consciousness".
Most people are not very "conscious". In that sense, most people are not much more of a superior organism than any of the higher mammals.
Most people are living life in a constant state of being in an instinctive, animalistic, biological "ground state". They are usually so "un-conscious" that they are effectively trapped in a semi-hypnotic trance, most of the time. In that sense, most people are not fully "awake" - they are mostly "asleep".
To grow a "soul" is to get steadily more practiced and skillful at actively maintaining your mind in a state of "consciousness".
MINDFULNESS is one extremely effective way of achieving heightened state of consciousness.
If you can maintain constant Mindfulness, you can maintain constant consciousness.
Another word used to describe the state of living in a sustained state of Constant Consciousness is "ENLIGHTENMENT".
Some quotes on what it means to stay in a state of heightened awareness, hyper-consciousness, or "enlightenment":
"Before Enlightenment: Chopping wood and carrying water. After Enlightenment: Chopping wood and carrying water."
Kuòān Shīyuǎn's "Ten Bulls"
Verses by Kuòān Shīyuǎn translation by Senzaki Nyogen (千崎如幻) and Paul Reps
The Ten Bulls:
1. In Search of the Bull
In the pasture of the world,
I endlessly push aside the tall
grasses in search of the Ox.
Following unnamed rivers,
lost upon the interpenetrating
paths of distant mountains,
My strength failing and my vitality exhausted, I cannot find the Ox.
2. Discovery of the Footprints
Along the riverbank under the trees,
I discover footprints.
Even under the fragrant grass,
I see his prints.
Deep in remote mountains they are found.
These traces can no more be hidden
than one's nose, looking heavenward.
3. Perceiving the Bull
I hear the song of the nightingale.
The sun is warm, the wind is mild,
willows are green along the shore -
Here no Ox can hide!
What artist can draw that massive head,
those majestic horns?
4. Catching the Bull
I seize him with a terrific struggle.
His great will and power
are inexhaustible.
He charges to the high plateau
far above the cloud-mists,
Or in an impenetrable ravine he stands.
5. Taming the Bull
The whip and rope are necessary,
Else he might stray off down
some dusty road.
Being well-trained, he becomes
naturally gentle.
Then, unfettered, he obeys his master.
6. Riding the Bull Home
Mounting the Ox, slowly
I return homeward.
The voice of my flute intones
through the evening.
Measuring with hand-beats
the pulsating harmony,
I direct the endless rhythm.
Whoever hears this melody
will join me.
7. The Bull Transcended
Astride the Ox, I reach home.
I am serene. The Ox too can rest.
The dawn has come. In blissful repose,
Within my thatched dwelling
I have abandoned the whip and ropes.
8. Both Bull and Self Transcended
Whip, rope, person, and Ox -
all merge in No Thing.
This heaven is so vast,
no message can stain it.
How may a snowflake exist
in a raging fire.
Here are the footprints of
the Ancestors.
9. Reaching the Source
Too many steps have been taken
returning to the root and the source.
Better to have been blind and deaf
from the beginning!
Dwelling in one's true abode,
unconcerned with and without -
The river flows tranquilly on
and the flowers are red.
10. Return to Society
Barefooted and naked of breast,
I mingle with the people of the world.
My clothes are ragged and dust-laden,
and I am ever blissful.
I use no magic to extend my life;
Now, before me, the dead trees
become alive.
