What is the difference between primary and secondary sources

Primary sources are things that have direct evidence about an event or person, such as the declaration or independence, eyewitnesses, conclusions of experiments.

Secondary sources are things that can be about the same thing as a primary source but they were created later on, like textbooks, the internet, and articles.  

roosevelt believed that in light of the country's recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. this belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of roosevelt's foreign policy.