Thus, a dis- tinctive cause homogeneous with that art which is the means of attaining the material body-an unexcelled
specialty lacking in other vehicles, other Tantras, and the first stage [of Unexcelled Yoga] - is necessary in the context of the perfection stage.
Thurman-Robert-a-F-Tr-Tsong-Khapa-Losang-Drakpa-Brilliant-Illumination-of-the-Lamp-of-the-Five-Stages