It was a popular story, and unsurprisingly so, for it was based around the chilling words of the girl herself.* It was the perfect example of the sin and destruction that awaited those who left the Message. If we left, we could rest assured, without the Message we would fall apart. This version of the story is taken from The Sin of Unbelief, May 17, 1958: Sometime ago, I was speaking to a girl. I felt led just to say something to her.
Definition of duration: Period required to complete an activity, job, or task, usually excluding holidays and other non-working days.
Macaulay duration is a time measure with units in years, and really makes sense only for an instrument with fixed cash flows. For a standard bond the Macaulay duration will be between 0 and the maturity of the bond. It is equal to the maturity if and only if the bond is a zero-coupon bond. Modified duration, on the other hand, is a derivative (rate of change) of price and measures the percentage rate of change of price with respect to yield.