Jeni,
I think, perhaps, that he is questioning whether fear is extrinsic in that some outside force or thing stimulates the emotion of fear or whether it is intrinsic in that it is a natural, inborn instinct that is there from the start and we experience fear as a reaction to something inadequate about ourselves that allows the emotion to manifest itself.
But, I could be wrong.
I think it's both but could never be only one or the other. I think it is an intrinsic emotion that sees the light of day when an extrinsic thing or force causes us to question ourselves and our capability to overcome it.
Without the extrinsic force, we would never experience fear. SOMETHING causes us to react: society, sickness, large crowds, etc.