If Jié has appeared in your reading, the book is naming the configuration of right limitation. Water above the lake — the inflow held by the banks. Without the banks the water disperses into nothing useful; with banks that are too tight, the lake stagnates. The character itself originally referred to the joint of a bamboo stem, the natural unit of measure that gives the plant its segmented strength.

Classical commentary reads this hexagram as the discipline of finding the right limit rather than the strongest one. The judgment's warning — 苦節不可貞, bitter limitation cannot be persisted in — is unusual in the book for naming a kind of discipline that does not work. Asceticism for its own sake, restraint that has become punishment, structure that has lost its life: these are not the hexagram's clearance.

What the book counsels is the careful work of measure itself. 制數度, 議德行 — devise the numbers and measures, examine virtue and conduct. The reader is being asked to set limits in proportion to what the limits are for — and to revise the limits as the conditions change. A bank that worked last year may now be too tight or too wide. The hexagram appears when the question is whether the current measures are still the right ones.

Jié's failure mode is the rigid maintenance of limits that have outlived their purpose. The book is alert to it. The hexagram appears when the reader is at the moment of evaluating the structures they have set — schedules, budgets, commitments, rules — and the temptation is either to maintain them past their usefulness or to abandon them altogether. The book counsels neither. Adjust the bank to the river the river has actually become.