Answer:
“The White Man’s Burden” presents the conquering of non-white races as white people's selfless moral duty. This conquest, according to the poem, is not for personal or national benefit, but rather for the gain of others—specifically, for the gain of the conquered. The white race will “serve [their] captives’ need” rather than their own, and the white conquerors “seek another’s profit, / And work another’s gain.” Even if they do not recognize their benefit, the non-white races will be brought “(Ah, slowly!) toward the light,” escaping the “loved Egyptian night” in which they idled before their conquest. Yet the non-whites’ positive sentiment for their own “darkness” indicates the extreme difficulty whites will face in seeking to educate the conquered peoples.
By emphasizing the hardships of this "burden," the speaker positions himself as a realist who sees all the difficulties of an imperialist project and the inevitable thanklessness that results. The speaker announces that imperial conquest will “bind your sons to exile” and cause them to “wait in heavy harness” in pursuit of the “savage wars of peace,” indications of the difficulty and tedium of the inevitable war. The “silent, sullen peoples” lifted up from “bondage” will never offer the imperialists any thanks or praise.
By taking the difficulty and thanklessness of imperialism seriously, the speaker establishes his credibility as someone of clear-sighted judgement. This stance of realism offers the speaker’s argument two key things. First, it staves off the retort that the speaker is some idealist blinded by an impossible dream. The speaker’s focus on the difficulty of the task actually has the effect of making that task seem, eventually, achievable, since all the difficulties have already been foreseen. Second, it sets up the speaker (and the European powers the speaker seems connected to) as a kind of stern, realist father figure to America who will offer Americans true respect—“the judgement of your peers” both “cold” and “edged with dear-bought wisdom”—if they fulfill their imperialist task.
Indeed, the poem in many ways appeals to the middle-class virtues of ordinary turn of the 20th century Americans by presenting imperialism as a sober, tedious duty rather than a grand adventure of conquest. Imperialism is a “toil of serf and sweeper,” not a “tawdry rule of kings.” The larger part of “the white man’s burden” is thus an exercise in “patience,” accepting the length and difficulty of the task set for the imperialists. Not a calling to a high heroic destiny, but a crude, almost homely task, imperialism suits the desires of those who imagine themselves honest workers on humanity’s behalf, rather than triumphant conquerors of weaker peoples. Put another way, the poem can be seen as cannily playing to the vanity of America precisely by refusing to play to its vanity. The poem is saying to an America that, in 1899, was feeling itself ready to emerge on the world stage: this is how you can stop being a child and grow up.
While the speaker of “The White Man’s Burden” can be seen as trying to cannily build an argument that will specifically appeal to a certain set of Americans, it also seems possible that the speaker is not being purely cynical. The speaker seems to believe everything he is saying: that imperialism and colonialism is a thankless task, taken up by whites purely out of goodwill for other races (even if those other races lack the ability to see the gift being bestowed upon them), without any ulterior motive of profit, reward, praise, or even gratitude. This enterprise may not even succeed; references to the task’s difficulty far outnumber references to its success. Thus even as the speaker believes it is the white man's duty to engage in conquest, he may also believe that this conquest will fall short of its moral goals. Imperialism, the speaker sincerely believes, is the white man’s gracious sacrifice on behalf of non-whites.
Explanation:
all of that^ is basically a theme of colonialism and imperialism, hope it helps:)