Secondary sources are accounts written "after the fact" and with the benefit of hindsight (greater understanding of the incident). They are normally interpretions and evaluations of primary sources. Secondary sources are not evidence, since they provide commentary on and discussion of the evidence.
From: "Primary, Secondary and Tertiary Sources." Univeristy of Maryland, Univeristy Libraries. 1 March 2013. Web. 3 October, 2013.
Context is everything, so whether a source is primary (original) depends on how it was created and its relation to research being performed.