Pliny the Elder was a Roman author, naturalist and military commander whose encyclopedic Naturalis Historia (c. AD 77) preserves the earliest known form of this thought: “How many things, too, are looked upon as quite impossible, until they have been actually effected?” The sentiment resurfaced across the centuries — in Daniel Wilson (1862), rocket pioneer Robert H. Goddard (1921) and SF writer Robert Heinlein (1951) — long before its crisp modern wording was pinned, without evidence, on Nelson Mandela around 2001.