In his chapter on silk reeling, in the book on Chen Style Tai Chi Chuan (1963) (A snip at only 828 pounds on Amazon in the UK!), Shen Jiazhen writes:

…Tai Chi Chuan movements must be in a shape like pulling silk. Pulling silk [from a cocoon] is done by a circular motion, and because it combines pulling straight and circling, naturally it forms a spiraling shape, which is the unification of the opposites of straight and curved. Silk reeling energy or pulling silk energy both refer to this idea. Because in the process of unreeling, extending out and pulling back the four limbs likewise produce a sort of spiraling shape, therefore the boxing manuals say that whether in large, extended movements or compact, small movements, one must absolutely never depart from this type of Tai Chi energy which unites opposites. Once one has trained in this thoroughly, this silk reeling circle tends to become smaller the more one practices, until one gets to the realm where there is a circle but no circle is apparent, at which point it is known only by intent. ¹ This is why the third characteristic of Tai Chi Chuan is that it is an exercise which unifies opposites with silk reeling, both forward and backward.

Thanks to Jerry K for the translation. If you’re interested he’s also translated other chapter of the book – like this one on Empty and Full.

With this in mind I thought it would be beneficial to investigate exactly how silk is pulled from a cocoon. The Chinese have cultivated silk worms for more than 5,000 years. Here’s video showing how silk is cultivated today in Shanghai:

Like any industry, silk production has been automated, but you can still see how people did it using a hand reeling machine in some parts of China:

I’m guessing that the initial spiralling action of her hand she uses to get the starter threads off the brush is where the analogy starts to happen with what you’re doing in silk reeling exercises in Tai Chi Chuan? It reminds me of the way you can play with an elastic band in your hand. With 5,000 years of silk production in China I’m pretty sure the hand reeling machines would have existed at the time Chen style was creating these exercises, some 300-odd years ago, but without a machine then you’d have to be doing it with your hands in that manner.

Either way, I don’t think the silk worm gets out of this alive 😦