Define straight line.
I know for a fact that there are straight lines in nature. Just the other day a fox came up to me and said “Buddy, can you help me out, I haven’t had a bite in three days”.
Did you bite him?
I have a rather large bar of cultured (man made) quartz on my desk. It has several windows and the lines that border those windows are straight; if they weren’t I believe the cultured quartz industry would fold in a matter of days.
Art teachers always say, “There are no straight lines in nature,” because they are instructing whiny students who always complain about their inability to draw a straight line, and the teachers are not getting paid enough to come up with a new reply every time.