Answer:
The poet sees the British Empire as a force that will keep growing. It's as if he speaks to it (he uses the pronoun thy - an old word for your), telling it that its boundaries will keep spreading wider and wider.
Step-by-step explanation:
The given lines are from the song Land of Hope and Glory - a British patriotic song composed by Edward Elgar in 1901. The following lyrics were written by poet Arthur Christopher Benson in 1902:
Land of Hope and Glory, Mother of the Free,
How shall we extol thee, who are born of thee?
Wider still and wider shall thy bounds be set;
God, who made thee mighty, make thee mightier yet,
God, who made thee mighty, make thee mightier yet.
The British Empire was the largest empire that ever existed. By 1920, it covered 24% of the Earth's total land area. Benson sees the British Empire as a force that will keep growing. It's as if he speaks to it (he calls it the Land of Hope and Glory, Mother of the Free, and uses the pronouns thee and thy - old words for you and your), telling it that its boundaries will keep spreading wider and wider.