Lines 12-13
At God’s bidding or will, thousands of people and by implication angelic messengers “speed and post” all over the world all the time. This line implies a sort of constant worldwide motion of service to God’s commands; that allows the last line to imply by contrast a great restfulness and peace. There is more than one way to serve God, and patience is telling the poet that even his waiting or the apparent inaction caused by his blindness can be a kind of service if it meets the criterion of lines 10-11, to bear the yoke well.