The capitalized words emphasize the most powerful parts of the poem. If a person can stay calm and focused even in the face of life’s extremes, “Triumph and Disaster,” he can have the whole “Earth” and will have become a “Man.” The fact that Kipling ends the poem with the lowercase words “my son” shows that the poem offers advice for how a young person can become a successful adult. The shift from “son” to “Man” suggests the process of growing up.

This answer uses text evidence to connect the capitalized words to the meaning of the poem. The capitalized words emphasize what a young person should focus on in order to gain maturity.