In Sutras and other texts there are often mentioned conditions for the practice to be effective. Here are some examples:
From the Heart Sutra:
"Sariputra, any noble sons or daughters who wish to practice the perfection of wisdom should see this way:"
Who are the noble sons or daughters?
From the Sutra of the Past Vows of Earth Store Bodhisattva:
"If good men or women of the future hear this Bodhisattva’s name, praise him, behold and bow to him, call his name, make offerings to him, or if they draw, carve, cast, sculpt, or make lacquered images of him, such people will be reborn in the Heaven of the Thirty-Three one hundred times and will never fall into the Evil Paths."
So this instruction apparently is only for the good men or women. Who are they?
These good men and women are mentioned many times in this sutra (http://cttbusa.org/ess/earthstore12.htm). I have been trying to do some of these practices, but without success, is this because I don't belong to the group of good men and women, or are there some other conditions that is lacking?
I just read also in Torch of Certainty that when you do Vajrasattva purification practice, if the visualization is not continuous throughout the practice, then it utterly useless, and even if you do the practice forever it will not be successfull.
It is also often mentioned that one needs a sincere mind, a straightforward mind, a concentrated mind. That one needs to have faith, devotion, etc.
The formula seems to be: if this or that condition is not met, it is like boiling sand in order to get food, you will never succeed.
Why can't there be some practice, for instance a mantra, that you can do whether or not you belong to the noble family, if you are good or bad, that you can do with or without faith, devotion, concentration, sincerity... and that still is effective?
Do you know if there are any such practice available?

