"The White Man's Burden" is an 1899 imperialist poem by Rudyard Kipling.
Kipling was a staunch and unashamed imperialist, and went through phases where his sympathies for native peoples increased and decreased. "Burden" is an example of his stronger imperialist phase, where he requested that the still-fledgling United Stated take up imperialism from England and Europe. His implicit assumption about non-whites is stated clearly in the first stanza:
Take up the White Man’s burden—
Send forth the best ye breed—
Go send your sons to exile
To serve your captives' need
To wait in heavy harness
On fluttered folk and wild—
Your new-caught, sullen peoples,
Half devil and half child
(Kipling, "The White Man's Burden, historymatters.gmu)
This was standard public opinion at the time, that natives and non-whites were inferior to whites. Kipling showed that despite works like "Gunga Din," which showed native people in a superior moral light, he still regarded them as "half devil" -- or with an inherent nature of immorality -- and "half child -- or without the facilities to become fully educated and understanding adults. These views became less pronounced later in Kipling's life, and this poem was a favorite of President Theodore Roosevelt.