Water

Fire, at least in the form of burning incense, is important in several religions. But water is pretty big too. Here's Larkin on the subject:

If I were called in 
To construct a religion 
I should make use of water. 

Going to church 
Would entail a fording 
To dry, different clothes; 

My liturgy would employ 
Images of sousing, 
A furious devout drench, 

And I should raise in the east 
A glass of water 
Where any-angled light 
Would congregate endlessly.

That's all Christian-influenced, of course. The Taoist version is interesting too. Here is a nice introductory video (24 minutes long, on Taoism and martial arts), and here is the water-related philosophy of Bruce Lee.

And here's some of the Tao Te Bing:

28. Be a valley

.
Be a valley to which, by nature,
water flows

Be an example to which, by nature,
the lives of others flow

Keep in view the child’s mind which,
like water, flows

To be whole see whole
Consider opposites
See finite and infinite

Be newborn.  Being man
understand being’s portal, woman,
through which new life  flows

See dark and light
In honor be humble
In strength be weak

To have integrity means to know outer and inner
because to each the roots of selfhood reach

In the newborn, as in an uncarved block,
are imminent possibilities waiting to be formed

Wisdom keeps its wholeness
being many

(h/t http://www.3quarksdaily.com/).