Dear Chairman Harrison and Members of the DNC, I know some of you well. A few of you are among my oldest friends. Others of you I have never met. But all of you are my family, as public servants and fellow Americans. Families tell one another the truth, as best we are able with grace and love and, above all, with candor. When we take wrong turns, or fail to live up to our best selves, it is our family’s responsibility to hold up a mirror and recall us back to our true purpose and highest self-expression. And so I feel compelled to write to you now, because in my view, limited though it may…