The foundation of Mahayana tradition lies in the practice of Bodhicitta. The text Abhisamayalamkara states:
“The formation of an enlightened attitude (Bodhicitta) is the desire for enlightenment for the benefit of others”
For the attainment of enlightenment, Bodhicitta is essential at all bodhisattva levels. There is no Buddha or Bodhisattva who lacked it. So all the Highest Yoga Tantra deities who are depicted in sexual union with their consorts are, however, the embodiment of the union of Bodhicitta (male) and wisdom (female). It is said that enlightenment is impossible without these two aspects.