By contrast, the Portuguese voyages around Africa and, it was hoped, to India, were based on risky speculative notions, rumors, and suggestions. Unknown lands would have to be skirted, used as supply bases for food and water en route. The journey would go where Christian geography threatened mortal dangers, far below the equator. Portuguese discoveries, then, required a progressive, systematic, step-by-step national program for advances through the unknown. Columbus’ Enterprise of the Indies was a bold stroke, the significance of which would not be known for decades. The Portuguese voyagers were on a century-and-a-half enterprise, the actual meaning of which was imagined long in advance, the accomplishment of which was known immediately. Columbus’ greatest achievement was something he never even imagined, a by-product of his purposes, a consequence of unexpected facts. The Portuguese achievement was the product of a clear purpose, which required heavy national support. Here was a grand prototype of modern exploration.

“The Portuguese Discoverers”, from “The Discoverers”, Daniel J. Boorstin, The National Board for the Celebration of Portuguese Discoveries, Lisbon, 1987