In the Old Testament, King Solomon’s pool had a diameter of 10 cubits and a circumference of 30 cubits. This gives a value of pi = 3.
Suppose our instruments were not accurate enough to detect that pi is actually a bit more than 3. Or suppose we had a reigious conviction that pi must be a whole number. When measuring a circle with string, we would stretch the string a bit to accomodate the error.
One day a pedantic mathematician with a length of un-stretchy string would be sure to challenge this belief. To avoid being burnt at the stake, he (or she) suggests that space-time must be curved just enough to make pi ‘seem’ to be a bit more than 3. In other words the circle is 'really' shaped like a dutch cap and the diameter is being measured across the arc of a circle (see diagram below).
From God’s point of view it is exactly 3 of course!
This is dicussed in this Physics Forums link: