The only poem I ever memorised, after I sent my rat terrier off to the kennel to be adopted by a better family (I took pitty on her, being yelled at so much.. not by me) and found out she was instead euthanised:
Turn Again To LifeIf I should die and leave you here awhile,
Be not like others, sore and undone,
For my sake – turn again to life and smile
Nerving thy heart and trembling hand to do
Something to comfort other hearts than thine.
Complete those dear unfinished tasks of mine
And I, perchance, may therein comfort you.