There are perhaps too many poems written by poets about the process of writing poems, but I think this is one of the better ones. I like the image of the slowly filling pool, though I tend myself to think more in terms of electricity, a static of observation and emotion slowly building till it finds its discharge. 

A Time of Waiting

The moment comes when my sound senses
Warn me to keep the pot at a quiet simmer,
Conclude no rash decisions, enter into
No random friendships, check the runaway tongue
And fix my mind in a close caul of doubt –
Which is more difficult, maybe, than to face
Night-long assaults of lurking furies.

The pool lies almost empty; I watch it nursed
By a thin stream. Such idle intervals
Are from waning moon to the new – a moon always
Holds the cords of my heart. Then patience, hands;
Dabble your nerveless fingers in the shallows;
A time shall come when she has need of them.

Robert Graves