The Cauldron: The Sequence of the Hexagrams says, 'Nothing transforms things like a cauldron; hence it is received with The Cauldron.' The function of the cauldron is to transform things: turning the raw into cooked, changing the hard into soft.
Water and Fire cannot dwell together, yet it can bring them into mutual accord for use without harming one another; this is being able to transform things. This is why The Cauldron follows Revolution (Molting). As a hexagram, Li is above and Xun is below.
The reason it constitutes The Cauldron is drawn from its image and its meaning.
In drawing from its image, there are two aspects: speaking in terms of the whole body, the planted bottom forms the legs, the solid middle forms the belly holding things within, the two standing opposite at the top are the ears, and that traversing across the top is the carrying handle; this is the image of a cauldron.
Speaking in terms of the two component trigrams, the hollow center is above and there are legs below to support it, which is also the image of a cauldron.
In drawing from its meaning, Wood follows Fire; Xun means entering, carrying the sense of yielding compliance; Wood following Fire is the image of burning.
The uses of fire are only roasting and boiling; roasting requires no vessel, so the image of boiling is taken to make the cauldron; using Wood to enter Fire is the image of cooking. In fashioning utensils, the image is taken; but is the hexagram formed after the utensil?
The answer is: fashioning utensils takes from the image; the image resides in the hexagram, yet the hexagram does not necessarily precede the utensil.
The sage did not wait to see the hexagram before understanding the image; because the common multitude cannot understand the image, the hexagram was established to show it to them. The priority between hexagram and utensil does not impair the meaning.
Some might wonder: a cauldron is not a natural image, but man-made. The answer is: indeed it is man-made, yet cooking can transform things, and when shaped like this it can be used—this is nature, not human artifice. The same is true of The Well.
Although the utensil existed before the hexagram, what is taken is the image of the hexagram, and the hexagram in turn uses the utensil for its meaning. Speaking in terms of the hexagram's capacity, if one possesses the hexagram's capacity, one can bring about supreme prevalence.
It should merely read 'supreme prevalence' (yuán hēng); the text has the character 'good fortune' (jí) as a superfluous addition. The hexagram's capacity can achieve supreme prevalence, but does not yet imply supreme good fortune.
The Commentary on the Decision again only mentions 'supreme prevalence,' so its superfluity is evident. The Commentary on the Decision says: The Cauldron is an image. That the hexagram is The Cauldron takes the image of the cauldron.
That the cauldron is a vessel models the image of the hexagram. There is an image, and only then is there a vessel; and the hexagram in turn uses the vessel for its meaning.
The cauldron is a great vessel and a treasured sacred object; hence its making, form, and model are especially strict in following the image. The name 'cauldron' (dǐng) means correctness (zhèng); the ancients glossed fāng (square/upright) as correctness.
Speaking of its form, the ears stand opposite each other above, the legs stand divided below, and around the inside and outside, high and low, thick and thin, there is nothing that does not have its standard and utmost correctness.
Only with utmost correctness does it achieve an image of stability and gravity. Therefore the cauldron is a vessel modeled on the image; that the hexagram is The Cauldron is because of its image.