betsyjane

I found it!
The authors name is Jorge Luis Borges -

An excerpt:
"In the very oldest regions of Tlon, it is not an uncommon occurrence for lost objects to be duplicated. Two people are looking for a pencil; the first one finds it and says nothing; the second finds a second pencil, no less real, but more in keeping with his expectation. These secondary objects are called hronir and, even though awkward in form, are a little larger than the originals. Until recently, the hronir were the accidental children of absent-mindedness and forgetfulness. It seems improbable that the methodical production of them has been going on for almost a hundred years, but so it is stated in the eleventh volume....... The methodical development of hronir, states the eleventh volume, has been of enormous service to archaeologists. It has allowed them to question and even to modify the past, which nowadays is no less malleable or obedient than the future. One curious fact: the hronir of the second and third degree - that is, the hronir derived from another hron, and the hronir derived from the hron of a hron - exaggerate the flaws of the original; those of the fifth degree are almost uniform; those of the ninth can be confused with those of the second; and those of the eleventh degree have a purity of form which the originals do not possess. The process is a recurrent one; a hron of the twelfth degree begins to deteriorate in quality. Stranger and more perfect than any hron is sometimes the ur, which is a thing produced by suggestion, an object brought into being by hope. The great gold mask I mentioned previously is a distinguished example."