Inter-Office Envelopes

At work I frequently use those inter-office envelopes. You know the kind, always orange in color with the lines to insert 'from' and 'to' etc etc. Well, every so often I pull one from my stack and it won't have been used for almost ten years. The one I have in my hand right now was last used on April 20th, the year 2000, and yet it is in pristine condition. How does this happen? Where has this envelope been for the last decade? Did it go on a really long sabbatical? Why is it back? Is is Jesus? Who found it and did they wonder where it had been for the last ten years? This stuff boggles my mind, it really does.