The He Tu's dots look timeless, but their history is precise, and Richard Smith's study of the Yijing's career in Chinese thought tells it candidly. The names He Tu and Lo Shu are ancient, attested in the classics; the familiar diagrams of white and black dots are another matter. They surface in the Song dynasty, transmitted through a lineage of diagram masters that tradition traces back to the Daoist recluse Chen Tuan, and they were canonised when Zhu Xi, the great synthesizer of Neo-Confucianism, set them at the head of his edition of the Yijing. From that placement flowed centuries of tushu, diagram learning: cosmologists read the He Tu's pairs as the generation of the five phases, matched its numbers against the trigrams, and built from the two charts a complete numerical metaphysics. The confidence lasted until the Qing, when the philologist Hu Wei subjected the diagrams to withering documentary criticism, arguing that the dot figures were Song constructions with no warrant in the ancient texts, and that a millennium of speculation had been raised on a medieval drawing.
Modern scholarship has largely sustained the philology while keeping the larger point: whatever the age of the drawings, the habit of thinking they crystallise, that heaven and earth have numbers and that their pairing can be diagrammed, runs deep and early in Chinese thought. The He Tu is thus doubly instructive: a genuine ancient name, a medieval image, and a standing lesson in how traditions furnish their own antiquity.