Strabo reported that Pytheas said he "travelled over the whole of Britain that was accessible". Because there is scant first hand sources available regarding Pytheas's journey, historians have looked at the etymology for clues about the route he took up the north Atlantic. The word "epelthein", at root "come upon", does not imply any specific method, and Pytheas did not elaborate. He did use the word "whole" and he stated a "perimetros" ("perimeter") of more than 40,000 stadia. Using Herodotus' standard of for one stadium gives ; however, there is no way to tell which standard foot was in effect. The English foot is an approximation. Strabo wanted to discredit Pytheas on the grounds that 40,000 stadia is outrageously high and cannot be real.