The Union of the Sun and Moon () is one of the seventeen tantras of the esoteric instruction cycle () which are a suite of tantras known variously as Nyingtik, Upadesha or Menngagde within Dzogchen discourse.
Namkha'i and Shane (1986, 1999: p. 91) open the discourse of the 'Song of the Vajra' (Wylie: rdo rje'i glu zhig) an excerpt of the Union of the Sun and Moon into the English language and render it thus: