Though not always necessary, what is the value of utilizing secondary source textual evidence in your supporting evidence about plays?

A secondary source is usually a professional or closely-related person to an incident. For example, take the September 11 attacks on the World Trade Center. Primary Source: Survivor from the buildings, a diary, a phone call recording from someone inside the planes. Secondary Source: Child of a victim, a firefighter, a news outlet. Tertiary Source: Unbiased outside perspective, such as a textbook. Utilizing secondary sources adds a layer of comprehension and relating to the reader.