The Spice Route by John Keay

"The human body needs minerals, notably salt; but pepper, the most substantially traded of all spices, is a dietary irrelevance. One might live a perfectly healthy life without ever ingesting, inhaling or otherwise being exposed to any one of the desiccated bits of vegatation that have traditionally been considered spices. Nor are they addictive in any physiological sense. The withdrawal symptoms might be evinced at times of scarcity were purely social and economic."