Serendipity is an unplanned fortunate discovery. Serendipity is a common occurrence throughout the history of product invention and scientific discovery.
Alexander Fleming's discovery of penicillin is an oft-cited example of serendipity.
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Velcro
Penicillin
Horatio Walpole, 4th Earl of Orford, better known as Horace Walpole, was an English writer, art historian, man of letters, antiquarian, and Whig politician.
Portrait by Sir Joshua Reynolds, 1756
Walpole by Rosalba Carriera, c. 1741.
Strawberry Hill House in Twickenham
Horace Walpole by John Giles Eccardt, c. 1755.