I am looking for details re a quote I found in Iain Murray's insightful biography on Jonathan Edwards. The quote is by Dr John Duncan: "I would like to sit at Jonathan Edwards feet to learn what true religion is, and at Thomas Boston's to learn how to get it." I understand Dr Duncan refers to Edwards Religious Affections. Does anyone know what Boston work he refers to? I assume it is Boston's classic Human Nature in Its Fourfold State, but I'm not sure. Any insights would be appreciated.