Preaching Plus

There might be variations of homiletical math. In my teaching of Haddon Robinson’s philosophy of preaching I instruct my students that to get the idea of a passage one uses the following homiletical math formula: S + C = I. That is, subject question plus the complement answer equals the exegetical idea.
But it strikes me that we can apply homiletical math to other areas of preaching. We could call this formula “preaching plus.” That is, preaching can be considered as an addition to a given area of study. For example, preaching plus history directs us to discover how and if preaching has had an impact in historical development in any culture or context. Preaching plus psychology may help us to discover how preaching intersects with the field of psychology. Further examples may come to your
mind. But the point here is to help us to see that the intersection of preaching with other fields and situations or contexts is far-reaching.