With the major exception of the Yi jing, we have neither formal canons nor commentaries for most early Chinese mantic traditions. Indirect reflections on these traditions appear in scattered commentaries, in biographical narratives, and, importantly, in excavated texts. The major source for mantic materials from the received textual tradition is the lists of their titles in Han shu 30, the “Yiwen zhi” or Bibliographic Treatise. It is a guide to the categories of knowledge used by Han thinkers, and created an influential paradigm for the classification of texts and knowledge. The present study provides a necessarily selective survey of mantic texts in the “Yiwen zhi,” with a specific view to: (1) how it underscored the authority of some techniques and marginalized others; (2) its relation to what we know of Han mantic practices; and (3) what it reveals about the role of the mantic arts as constituents of scientific observation and systematic inquiry in early China.