To paraphrase an old saying: Everybody complains about the way obsolescence is handled in tax depreciation practice, but nobody has as yet found a solution that satisfies both the taxpayer and the tax collector. It is obvious that this problem is much too big to treat in detail in this short article, but an attempt will be made to discuss several aspects of the problem which the writer believes either have not been fully understood by most persons, or else have not been explained sufficiently by those who advocate certain procedures. In order to develop the subject adequately, it will be necessary to investigate certain matters not directly concerned with tax practice