Why does Milton refer to the Biblical parable of the talents in his poem "When I consider how my light is spent?"

The poet John Milton became blind later in his life, and
this sonnet is one of the first that he wrote about his condition. The Biblical parable
of the talents relates how a man who does not use his God-given talents while on earth
will be punished, and Milton refers to it here because he is wondering how he will
employ his talent as a poet to its fullest extent now that he is blind. Milton calls his
gift "that one talent which is death to hide," but says it is "Lodg'd with me useless,"
now that is vision, or "light," is "spent." He would like to continue serving God with
his gift, so that he will not be "chide[d]" or scolded when God calls him to account,
but he wonders, "Does God exact day-labour, light denied," questioning whether God still
expects him to work as he did before, now that he can no longer see. The Biblical
parable is directly related to what the poet fears - that he will still be held
accountable for using his gift as he did before, even though he is now
blind.

Upon reflection, the poet finds consolation in the
realization that God, who is almighty, does not need his paltry work. God is merciful
and understanding, and Milton, now blind, can still serve him by being patient, and
bearing his suffering without complaint - "who best bear his mild yoke, they serve him
best." God's mercy transcends the literal message of the Biblical parable, and the poet
is consoled with the realization that "They also serve who only stand and
wait."