Read the passage.
when an epidemic of physical disease starts to spread, the community approves and joins in a quarantine of the patients in order to protect the health of the community against the spread of the disease.

why is this passage effective in supporting roosevelt's argument?

it compares aggressive natures to something that everyone can agree must be contained: a dangerous physical disease.

it demonstrates that what roosevelt is proposing has worked in other nations, at other times

it sparks enough hatred of the enemy in the hearts of the american people that they will act of their own accord

it acknowledges that fighting the aggressors will be hard work, which makes sense considering that america has an admirable work ethic.