A secondary source would be the newspaper coverage of Roosevelt's speech the next day. The greatest strength of a primary source is that you can actually see or hear what was said at the time. The document does not know what the future holds. You can interpret what was said for yourself. It is history, sitting there for you to behold.
Secondary documents have the advantage of hindsight.
They can know what the future holds. They also provide some needed context to help the primary document make sense. For instance, you may get a primary document announcing the launching of Sputnik. It will probably seem rather bland. Since you are doing history you essentially want to take the primary documents and, with your own knowledge, create the context.