“Primary” and “Secondary Reflection” are concepts from the work of Christian Existentialist Gabriel Marcel. To provide a rough and inaccurate summary, primary reflection is the initial attempt to mentally apprehend an external reality as something foreign and separate, whereas secondary reflection is considers the subject as part of the larger whole within which the observer and the observed are neither separate nor separable.
From an existential point of view, when we view the world as made up of external objects distanced from ourselves, we lose awareness of our ability to influence the reality seemingly composed by such objects. It is only when we understand the extent to which personal identity extends outwards into the world that we embrace our freedom to shape the reality in which we live.
To my regret and shame, I must admit that I am no scholar of Marcel’s work –an unforgivable omission for a Christian Existentialist such as myself –so much of what I have said may be untrue to his original vision. If this is a topic that interests you, I recommend you consult his works, of which The Mystery of Being is one of the most famous.