A traditional cloth sole begins with things that would otherwise be thrown away. Worn cotton is brushed with a thin starch paste, laid flat, and built up sheet by sheet into a stiff board. Several of these boards are cut to the outline of a foot, stacked, wrapped at the edge, and then sewn through with row after row of dense stitches using a heavy linen or hemp thread. Nothing in that list sounds like engineering. It is, though: every step answers a specific failure that a single thick piece of material would suffer.
Start with the obvious alternative — one slab of felt or one thick piece of leather. Bend it repeatedly and the outer face of the bend stretches while the inner face compresses. In a solid slab the two are locked together, so the strain concentrates at one line and a crease forms; keep going and the crease becomes a crack. A stack of thin layers behaves differently. Each layer can shift by a fraction of a millimetre against its neighbours, so the bend spreads over a longer arc, and the friction between layers dissipates some of the energy of every step. The sole flexes without ever asking one line of fibre to take the whole bend.
What the stitching actually does
Loose layers would simply slide apart and bunch up inside the shoe, so the thread rows are the structure. They clamp the stack into something that behaves like one plate under compression but still permits that small amount of shear. The density is a compromise: too few stitches and the layers creep, forming a hard lump under the ball of the foot; too many and the needle perforations start to join up, the cloth tears along the rows, and the sole becomes wooden. Old makers judged this by feel and by the sound the needle made going through, which is a reasonable way to measure a property that is hard to see.
The starch paste has two jobs and neither is permanent. While the sole is being made it stiffens the scraps so they can be cut and stacked cleanly. In wear it adds friction between layers and a little rigidity, but it is water-soluble enough to soften with sweat and rain. That is why a new pair feels stiff and a worn pair feels made for one particular foot: the stack has slowly taken a set. Quilting a padded jacket uses the same idea for the opposite reason — there the stitching stops loose fibre from migrating, here it keeps flat layers from sliding. Both are thread paths doing the work of an adhesive.
Why cloth rather than a solid sheet
The material choice brings advantages that have nothing to do with nostalgia. A layered cloth sole breathes and takes up moisture, so it is comfortable in heat; it is quiet on hard floors; it can be patched by sewing on a new layer, and it can be resoled without special tools. It also has a clear weakness: soak it thoroughly and the starch softens, the layers lose their grip, and the edge wears quickly on wet grit. That is why footwear follows the ground it is made for — dry paving and indoor floors suit this construction, and a muddy monsoon climate asks for something else.
There is an instructive comparison with felt, which needs no loom at all. Felt is a mass of fibres locked by their own scales, with no layers and no thread; it is warm and springy but has no internal shear planes to spread a bend. The cloth sole goes the other way, deliberately introducing dozens of interfaces. One material wins by having no structure, the other by having a great deal of it.
So the visible thrift — old shirts, paste, a needle — is not the whole explanation. Anyone with a thick piece of hide could have made a sole in an afternoon. The layered version takes days, and the reason to spend them is mechanical: it turns a material that would fail at one crease into one that wears down slowly and evenly, all over, at roughly the same rate as the upper it is sewn to.
Take a small stack of paper and a single card of the same total thickness, then bend both back and forth twenty times. The card develops one sharp fold and soon tears along it. The stack curves smoothly and stays intact. The cloth sole is that observation, made washable and sewn to a shoe.