The Large Intestine Meridian is known as the
"Drainer of the Dregs". 

It is about our ability to let go of what is not needed from our body, mind, spirit and emotions.

Thus helping us to stay clean and not cloggeged up with what no longer serves us.
The Five Elements in Nature
Autumn is the energy of Metal, the time when nature rids itself of what is not needed, when nature sheds its leaves and lets go of the rubbish it no longer needs. With those leaves it produces its own compost, enriching the soil, ensuring the next cycle has the nutrients it needs to grow. 
Autumn and Metal
Metal is about our own purity, our spiritual essence, our ability to have connection with a 'heavenly father'.
The Lung Meridian is the "Receiver of Heavenly Qi" giving us the ability to receive pure qi, connection to the spirit and real connection to others.
By giving us connection to the heavenly realms Metal helps us understand that we are more than the 'day to day' of life, that we are connected to 'all that is' and in that it
is the source of our real self esteem.
Metal is the source of such emotions as good self esteem, loyalty, conceit, and longing for what has been.
Spring and Wood
Summer and Fire
Late Summer and Earth
Autumn and Metal
Winter and Water