The subsequent work showing the independence of AC from the other axioms of set theory vindicates Zermelo's pioneering work; in this respect, it puts Zermelo's revelation of the choice principle in a similar position as that which Hilbert ascribes to the Parallel Postulate in Euclid's work. Hilbert claims that Euclid must have realised that to establish certain ‘obvious’ facts about triangles, rectangles etc., an entirely new axiom (Euclid's Parallel Postulate) was necessary, and moreover that Gauß was the first mathematician ‘for 2100 years’ to see that Euclid had been right (see Hallett and Majer 2004:261–263 and 343–345). This ‘pragmatic attitude’, which is on display in Zermelo's second paper on well-ordering from 1908, became, in effect, the reigning attitude towards the choice principle: If certain problems are to be solved, then the choice principle must be adopted. In 1908, Zermelo brings out this parallel explicitly: