In "The Franklin's Tale," from Chaucer's fourteenth-century Canterbury Tales, a Clerk uses medieval astronomical tables, calculating lunar and solar positions, to predict an extraordinarily high flood tide. Literary scholar Phyllis Hodgson has concluded that Chaucer's purpose here is artistic, not scientific, and that even though Chaucer was a master of astronomy and author of an astrolabe treatise, this "highly technical account of the Clerk's astrological calculations need not be taken too seriously." Recently, however, astronomer Don Olson concluded that Chaucer's account actually describes a very rare astronomical configuration of the Sun, Moon, and Earth that produced an exceptionally high tide in December 1340. But why would Chaucer be aware of a high tide that occurred in 1340, some five decades before "The Franklin's Tale" was written some scholars place Chaucer's birth in late 1340 or early 1340. When Chaucer was studying astronomy during the 1380s and 1390s, it is plausible that he investigated his own horoscope. Chaucer may have discovered the remarkable tide-raising configuration in 1340 while calculating celestial positions at the time of his own birth and then used this knowledge as inspiration for the plot device in "The Franklin's Tale."