According to the above differentiation between the tzadik and the beinoni, the meaning of “a person cannot transfer ownership over an article that has not yet come into existence” can be understood in regard to one’s service of G-d.
A person who is holding on the level of a beinoni—one whose “produce” is acquired by G-d, but not his “person”—must know that he only has jurisdiction over the present, and not the future. While he can control his thought, speech or action that he has at the current moment, he cannot “transfer the ownership” of any future action in order that it too, will be in accordance with G-d’s will.
If such an individual makes a resolution that all his future actions will only be good and in accordance with G-d’s will, he does not make any “acquisition” through such a proclamation.
Although he has made a resolution, his words are meaningless, as there is no way to guarantee that indeed his future actions will be fitting with G-d’s desire, as he has no control over the experiences that are yet to come.
Text 9
The evil in the [heart's] left part of the beinoni is in its innate strength, craving after all the pleasures of this world, not having been nullified in its minuteness in relation to the good, nor having been relegated from its position to any degree.
Tanya, Ch. 13
Since a beinoni, by definition, is a person whose heart and mind crave evil, he cannot guarantee that in the future all his actions will be good. Rather, he must be in a constant state of battle with his evil inclination in order not to allow the lusts of his heart to come to fruition. No matter what resolution he has made concerning his future actions, when he is faced with a challenge, it is entirely possible that he will falter and be overpowered by the evil desires that are still in his heart.
