Why prepare a treatise on Heartwood and Tree Exudates? Why consider both topics together? What approach should be taken in their treatment? The exudates were one of the earliest items of trade between family, tribal, and racial groupings in prehistoric times. They became used extensively as items for the manufacture of implements and as commercial goods for illumination, for cosmetic, religious and magical purposes. Later heartwood from various trees entered intra and international trade for prestigious and religious buildings (when cedars were used), for the furniture (e.g., ebony, mahogany)...