The key ideas of the speech are that Americans must maintain faith, courage, and hope even if it seems impossible to maintain them. He develops these ideas by reinforcing how these feelings build what a person is and should be. These ideas help form the theme that resilience is what builds duty, honor, and country.
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In that case, he asserts that Americans must be resilient, as this is what built honor and duty to the country, allowing for the safety and protection of America and its constituents.
More information about a theme of a text:
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