The core Zhouyi layer dates to the Western Zhou (roughly 1000-750 BCE): hexagram figures with terse line statements. The Ten Wings commentary, including the Xici Zhuan with the Taiji sequence, accrued in the Warring States to Han. King Wen and the Duke of Zhou are the traditional authors; the text is actually a multi-century sediment.
Three thousand years of coin-tossers report the same eerie property: the answer is never wrong because it is never specific. Skeptics call it a mirror; devotees call it resonance; both describe the same mechanics.
The structural fact: 64 hexagrams are 2 to the 6th power, a complete binary space assembled by a civilization that never wrote zero. Whether this is a profound mathematical intuition or an inevitable artifact of doubling is the argument that reached Leibniz and never ended.
Is it a book that answers questions, or a machine for revealing the questioner?