# Who was the first person who emphasis the importance of proof?

I think it should be an ancient Greek mathematician who was interested in proving all triangle has inner angles summing to 180 degree? Was it Thales?

• First one must define "proof." (and "important") I think this question is too vaguely worded to be answerable. – Carl Witthoft Dec 12 '18 at 14:30
• who was the first to emphasize the importance of proof ? That is on my practice final for history of math. – nafhgood Dec 12 '18 at 14:34
• If that is on the final, then the expected answer is probably in the readings (or the lectures) for that course. – Gerald Edgar Dec 12 '18 at 22:44