# Philosophy and Fun of Algebra/Chapter 9

CHAPTER IX THE USE OF SEWING CARDS
When you go for holidays perhaps your friends will ask you what is the use of sewing curves on cards. I should like you to know exactly what to say.
The use of the single sewing cards is to provide children in the kindergarten with the means of finding out the exact nature of the relation between one dimension and two.
There is another set of sewing cards which is made by laying two cards side by side on the table and pasting a tape over the crack between them. This tape forms a hinge. You can lay one card flat and stand the other edgeways upright, and lace patterns between them from one to the other.
The use of this part of the method is to provide girls in the higher forms with a means of learning the relation between two dimensions and three.
There is another set of models, the use of ​which is to provide people who have left school with a means of learning the relation between three dimensions and four.
The use of the books which are signed George Boole or Mary Everest Boole is to provide reasonable people, who have learned the logic of algebra conscientiously, with a means of teaching themselves the relations between n dimensions and n+1 dimensions, whatever number n may be.
The above is a quite accurate account of the real Boole Method; as much as there is any need for you to know while you are at school.
I should feel grateful to you if you will each copy it out in a clear handwriting, and keep it by you, and take it home whenever you go away from school for the holidays. It would be all the better if you learned it by heart.
And now I will tell you why I am so anxious about this.
The Boole method is a conveyance which will take you safety to wherever the Great Unknown directs you to go. Some people mistake it for the carpet in the Arabian Nights which took ​whoever stepped on it wherever he or she wished to go—which is a quite different thing. The true Boole method depends essentially on making a right use of imaginary hypotheses. The magic carpet depends for its efficacy on making a wrong use of imaginary hypotheses.
People get to very queer places on that carpet. I have been for several excursions on it, so I know.
One of the places it can take you to is a town where all the front doors open on to a street very like Regent Street; with the most gorgeous millinery, jewellery, and fruits in shop windows; and all the back doors open to wild country where blue roses, black tulips, and the fattest double carnations of all colours (including green ones) grow wild in the hedges and fields; and where all the pigs have wings.
Another place that it can take you to is one where pigs can wallow in all the filth they like without soiling their wings; and moths fly into candles without singling theirs.
The carpet will take you straight to whatever ​place you wish to go to. It is by no means warranted to take you safely back.
The advantage of Boole's method is that it is warranted to bring you safe down somewhere on solid earth,—not always the exact place you started from, but a safe and clean place of some kind—and to deposit you steady on your feet, with a compass in your pocket which will show you a straight way home.