The sacred spring was said to be in Pieria, a region of ancient Macedonia, also the location of Mount Olympus, and believed to be the home and the seat of worship of Orpheus. The Muses "were said to have frolicked about the Pierian springs soon after their birth". The spring is believed to be a fountain of knowledge that inspires whoever drinks from it.
An early reference to the Pierian spring is found in the Satyricon of Petronius, from the 1st century AD, at the end of section 5 (available online *)
In Greek mythology, it was believed that drinking from the Pierian Spring would bring you great knowledge and inspiration. Thus, Pope is explaining how if you only learn a little it can "intoxicate" you in such a way that makes you feel as though you know a great deal. However, when "drinking largely sobers" you, you become aware of how little you truly know.
The opening stanza also appears in Ray Bradbury's Fahrenheit 451, as Fire Captain Beatty chastizes Guy Montag, the protagonist, about reading books, which are forbidden in the society of the novel.
In his poem "Hugh Selwyn Mauberley," Ezra Pound refers to Pierian "roses" in a critique of the cheap aesthetic of his time, which in his opinion has replaced a true appreciation of art and knowledge:
"Conduct, on the other hand, the soul 'Which the highest cultures have nourished' To Fleet St. where Dr. Johnson flourished;
Beside this thoroughfare The sale of half-hose has Long since superseded the cultivation Of Pierian roses."
Sir William Jones (1746–1794) also made reference to "the fam'd Pierian rill" (a brook or rivulet) in his poem about the origin of chess, "Caissa".
^Orpheus and Greek Religion (Mythos Books) by William Keith Guthrie and L. Alderlink, 1993, ISBN 0-691-02499-5, page 62
^Classical Mythology in Literature, Art, and Music (Focus Texts: For Classical Language Study) by Philip Mayerson,2001, page 82: "... the Muses who were said to have frolicked about the Pierian springs soon after their birth. The Castalian spring on Mount Parnassus ..."
^E.C. Marchant, Commentary on Thucydides: Book 2,Πιερίας—between Mt. Olympus and the Thermaic Gulf, the original home of the muses and birth-place of Orpheus.