What does it mean to forgive?

‘Forgive our sins as we forgive,’
you taught us, Lord, to pray,
but you alone can grant us grace
to live the words we say.

How can your pardon reach and bless
the unforgiving heart,
that broods on wrongs and will not let
old bitterness depart?

In blazing light your cross reveals
the truth we dimly knew:
what trivial debts are owed to us,
how great our debt to you.

Lord, cleanse the depths within our souls,
and bid resentment cease;
then, bound to all in bonds of love,
our lives will spread your peace.