That is a great quote from the Upadesa! A little further down the page is:
There are two kinds of things that cannot be acquired:
1) Worldly pleasures, which can be sought but which do not respond to the attempt, cannot be acquired; 2) The true nature of dharmas, the definite notice (niyattanimitta) of which escapes perception, cannot be acquired. Not being non-existent, they include merit (puṇya) and increase the roots of good (kuśalamūla).
I do not get the last sentence. I am guessing that understanding (which is not perception) of the "true nature of dharmas" will increase merit & good.
Also the Upadesa quote and the general notion of shunyata being the true nature reminds me of an old problem in my mind. Je Rinpoche (among others) says that understanding fully emptiness, without compassion (or bodhicitta more exactly), will lead to being a Prateykabuddha. If compassion is not in the "true nature of dharmas" then it is a superimposition by the practitioner. Which is fine & dandy, for bodhicitta is certainly a much needed factor. But my gloomy tendencies concludes "this universe is naturally a truly cold, heartless place." It is hard enough going against the current of this humanity on this planet, but to think that the infinite universe has no native compassion! what a dark thought.
What is that verse by Shantideva about the rare "good" lightning flash versus the long night?