The purchase and stashing of yarn creates an interesting discussion between those who stash and their spouses. We who stash are accused of irresponsible spending and ignoring the laws of cubic space when we think that new purchases will fit in the space already allotted but seemingly full. Spouses are accused of not understanding and insensitivity to art, color and tactile sense.
I personally think that the division is between philosophy and psychology. Philosophy for all touting that it is reasonable is tailored to each person. A perception of what is art to me - my philosophy of art - is mine, not anyone else's. Each skein of yarn represents a piece of art to me - art in the touch and sight of it as well as in the vision of what it might become.
For spouses, the issue is "Are you crazy?" Another unreasonable "science" but different from philosophy. The answer to the question does not depend on what an individual may think but with what the DMMA IV defines as abnormal. The purchase of art is not abnormal much less crazy. Therefore, the question of craziness is answered with "No."
My philosophy of yarn is that I need at least one ball of each kind and brand of yarn in the world - at least one. I cannot judge the usefulness or the art-ability of any without comparing it to others. Plus, I must have a variety of colors in order to judge the quality of color and dyeing. So, I accumulate the necessary parts for appreciation of the art of yarn.
So far, this appreciation has covered one wall of my wall and flowed onto the floor in tubs and cloth boxes and baskets and canvas bags. My UFOs (unfinished objects) are multiplying as I just can't resist trying the new yarn (or new needles that just arrived to be compared). Occasionally, I must sort through the jungle and jumble to find needles that I need and pull the UFO off, tie it through with string and restore it to the UFO basket. Meanwhile, the freed needles immediately begin what might well be another UFO in a few days.
My spouse's question has changed to, "Is there a path in your study so that I can get to your computer if I need it while you're gone?" "Yes, but watch your step."
Peace and happy needling.