The phrase "standing on the shoulders of giants" is a metaphor which means "using the understanding gained by major thinkers who have gone before in order to make intellectual progress". It is a metaphor of dwarfs standing on the shoulders of giants () and expresses the meaning of "discovering truth by building on previous discoveries". This concept has been dated to the 12th century and, according to John of Salisbury, is attributed to Bernard of Chartres. But its most familiar and popular expression occurs in a 1675 letter by Isaac Newton: "if I have seen further [than others], it is by standing on the shoulders of giants." Early references Middle Ages An unknown attribution to Bernard of Chartres from John of Salisbury in 1159, John wrote in his Metalogicon: "Bernard of Chartres used to compare us to dwarfs perched on the shoulders of giants. He pointed out that we see more and farther than our predecessors, not because we have keener vision or greater height, but because we are lifted up and borne aloft on their gigantic stature." However, according to Umberto Eco, the most ancient attestation of the phrase dates back to Priscian cited by Guillaume de Conches. According to medieval historian Richard William Southern, Bernard was comparing contemporary 12th century scholars to the ancient scholars of Greece and Rome: A similar conceit also appears in a contemporary work on church history by Ordericus Vitalis. [The phrase] sums up the quality of the cathedral schools in the history of learning, and indeed characterizes the age which opened with Gerbert (950–1003) and Fulbert (960–1028) and closed in the first quarter of the 12th century with Peter Abelard. [The phrase] is not a great claim; neither, however, is it an example of abasement before the shrine of antiquity. It is a very shrewd and just remark, and the important and original point was the dwarf could see a little further than the giant. That this was possible was above all due to the cathedral schools with their lack of a well-rooted tradition and their freedom from a clearly defined routine of study. Religious texts The visual image (from Bernard of Chartres) appears in the stained glass of the south transept of Chartres Cathedral. The tall windows under the rose window show the four major prophets of the Hebrew Bible (Isaiah, Jeremiah, Ezekiel, and Daniel) as gigantic figures, and the four New