How do ideas spread? Previous research has focused on what happens to the sharers of an idea: what emotions they feel, what types of content inspire them to share (practical, funny, “sticky” and so on). And it is true that from memetics to mirror neurons to social contagion, it is likely that for any given idea, multiple factors are involved.  And yet the role of content seems to get all of the focus.  There are scores of books written about how to make your content “go viral” or “become contagious” and take on a life of its own. We seem to overlook — or at least undervalue — the role of the person delivering the idea: the carrier.