I was angry with my friend: 
I told my wrath, my wrath did end. 
I was angry with my foe: 
I told it not, my wrath did grow. 

And I water'd it in fears, 
Night and morning with my tears; 
And I sunned it with smiles, 
And with soft deceitful wiles. 

And it grew both day and night, 
Till it bore an apple bright; 
And my foe beheld it shine, 
And he knew that it was mine, 

And into my garden stole 
When the night had veil'd the pole: 
In the morning glad I see 
My foe outstretch'd beneath the tree. 

Wiliam Blake 
From Songs of Experience

with thanks to Peter Kalnin for pointing out the typo.
picture credit: http://www.polbox.com/m/maurycyk/drzewo.html