Sometimes, in order to understand the big picture, you need to be aware of the finer details.
So it is with fibres and yarn.
The above images are Scanning Electron Microscope images of, in this case, cotton.
The fibre once harvested 'collapses' into a flat ribbon with a twist in it. This gives the fibre some grip, or 'tooth'.
Silk (cultivated), on the other hand:
is much smoother, slipperier.
So by their very nature, the two fibres are quite different and will therefore behave quite differently.
Then add in the differences involved in preparing the fibres, then spinning them into yarn.
Weavers should be aware of these (literally) microscopic differences so that they have a better understanding of how the fibres/yarn will behave. In order to choose A Good Yarn.
I will be presenting this lecture at Fibres West on Friday morning. It's free with admission.
Having obtained these images for my use, they will also be incorporated into The Book, currently on hiatus while a beta reader completes the next round of edits. But hopefully back at it soon, refreshed.