Forever Is A Long Time

Two days ago I bought eight sheets of Forever Stamps anticipating today's postage increase. At the time of my purchase, the Post Office clerk asked if I wanted more of Forever. Her question stumped me. How far into Forever must a person buy to feel safe? And can eternity actually be purchased? I stuck with the eight sheets. I'm pretty sure I'll use them up within, say, a couple of years if I'm careful. If I'm not careful, I could probably squander forever in no time at all. In the meantime, it feels pretty good to own part of the future.