took me some time to understand but ^^ below the "lim" it shows that x ->c, ie replace "x" with "c" in "f(x)" , therefore giving the answer f(c). Thats it! MATHS! but the thing with limits "lim" is that "x" is not completely equal to "c" but it is almost equal to "c", but you kind of round it of.Hence in a perfect world x=c but since its Not a prefect world its x->c
A, uhm, continuous function would fulfill this if I recall correctly? Not sure about the joke though. Edit: Oh, I see, thanks for the explanation. ^^
that would actually be the the truth, the universe just has been created by imperfectness, some random not foreseen events =).