How does William Blake use vivid images in "A Poison Tree" to make his message clear?

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  • 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 waterd it in fears,                    5
      Night & 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.                              10
      And my foe beheld it shine.
      And he knew that it was mine.
  •   And into my garden stole,
      When the night had veild the pole;
      In the morning glad I see;                              15
      My foe outstretchd beneath the tree.

The images include the metaphor of harboring anger and nurturing a tree.  By keeping his wrath from his foe, he begins growing the tree.  He waters it with fears and tears day and night, suns it with smiles and deceit.  In other words, he acts friendly and harmless enough and entices the foe in closer with the "apple" which kills him.