This technique was taught a thousand years ago by Master Atisha, and the technique itself is possibly a lot older. It is perhaps the centre of the spiritual discipline known in Tibet as Loojong
Master Atisha had a particular of spiritual intrest: Speed and efficiency. Atisha was all about the most effective methods, most supportive attitudes and spiritual totality in general.
That's why his so concise description of this technique, quoted above, expresses the totality of this technique. The starting point, and the method were taught person to person. The text served as a reminder of the practice and a concise distillation of the full teaching.
This meditation is a key method for growing your heart centre and using it consciously. The core work of this school is the re-development of the Dakini's arts and practices, in ways appropriate to the world as it is now. This practice is one that we treasure as a glowing ember among the ashes of Ancient Tantra, which has contributed greatly to this school's fire, to the heart of this phoenix.
So, don't be daunted by Atisha's words, the scale of the aim he urges. If you're even just tasting, dabbling with the idea of Tantra perhaps being your path, just taste this, dabble with this too. Particularly if you get some knocks along with life's caresses.