"The White Man's Burden" has been criticized since its publication both for its condescending and ultimately dehumanizing view of seemingly all non-white peoples, and for its supposed lack of sophistication. The poem values realism and clarity, but there are several examples of metaphors in the text.
In the first stanza of the poem, Kipling uses the harness as a metaphor for service:
Go bind your sons to exile
To serve your captives' need;
To wait in heavy harness,
On fluttered folk and wild--
Later in the poem he uses "light" as a metaphor for civilization and "night" and "bondage" as metaphors for "savagery."
The cry of hosts ye humour
(Ah, slowly!) toward the light:--
"Why brought he us from bondage,
Our loved Egyptian night?"
Perhaps the most important metaphor in the poem, however, is not as obvious as these. Throughout the poem, imperialism is cast as a "burden," as in the title, but also in terms of "struggle" and "toil." It is an ordeal that will benefit them even if the recipients of western imperial "benevolence" do not appreciate it.