is the effect by which one accidentally discovers something fortunate, especially while looking for something else entirely. The word derives from an old Persian fairy tale and was coined by Horace Walpole on 28 January 1754 in a letter he wrote to his friend Horace Mann (not the same man as the famed American educator), an Englishman then living in Florence. The letter read,"It was once when I read a silly fairy tale, called The Three Princes of Serendip (Serendip = Sri Lanka): as their highnesses travelled, they were always making discoveries, by accidents and sagacity, of things which they were not in quest of: for instance, one of them discovered that a mule blind of the right eye had travelled the same road lately, because the grass was eaten only on the left side, where it was worse than on the right—now do you understand serendipity? One of the most remarkable instances of this accidental sagacity (for you must observe that no discovery of a thing you are looking for, comes under this description) was of my Lord Shaftsbury, who happening to dine at Lord Chancellor Clarendon's, found out the marriage of the Duke of York and Mrs. Hyde, by the respect with which her mother treated her at table."
The fairy tale The Three Princes of Serendip
is based upon the life of Persian King Bahram V, who ruled the Sassanid Empire (420–440). Stories of his rule are told in epic poetry of the region (Firdausi's Shahnameh of 1010, Nizami's Haft Paykar of 1197, Khusrau's Hasht Bihisht of 1302), parts of which are based upon historical facts with embellishments derived from folklore going back hundreds of years to oral traditions in India and The Book of One Thousand and One Nights. With the exception of the well-known camel story, English translations are very hard to come by.