As stated already, prayer confers upon man a capacity without which he may not have been fit to receive a certain benefit, by preparing and readying the petitioner for the Divine grace. The kindness of G-d, invoked by prayer, emanates to prospective recipients in accordance with their ability of receiving it.
This does not mean that the benefits received are in compensation for our good deeds. Indeed, "we do not present our supplications before You by virtue of our righteousness, but because of Your abundant compassion." (Daniel 9:18)
The kindness of G-d, and the mercies He bestows upon all His creatures, are based upon pure, gratuitous grace. They are not in the nature of compensation, as G-d said to Job: "Who has given Me anything beforehand that I should repay him" (Job 41:3).
Thus it follows that prayer can make a person fit to receive Divine benevolence even though he may be as wicked as King Menasseh, and the prayer was but forced by distress.
Nonetheless, there is a correspondence between man's status and the Supernal emanations. Generally speaking, Supernal decrees or determinations, of whatever kind, are conditional upon certain degrees, levels or dispositions of man. Thus it stands to reason that as that degree of disposition changes, then whatever had been determined also changes.
The problem of change, therefore, falls back upon the principle of "potentiality and actuality." G-d is not subject to change. Even with regards to new occurrences, innovations and seemingly novel developments on earth, it is said, "There is nothing new under the sun. If there be anything whereof it is said, `see this, it is new' - it has already been in the ages before us." (Ecclesiastes 1:9-10).
This means that even `new things' have been preconceived and prepared at the time of creation to become actualized and revealed at the proper time and under suitable conditions. There is then no change now at all, but merely the actualization of something which so far existed in potential.
It is likewise with prayer.
The Divine will provides, from the very beginning, that a change `below' (a real change in man, thus a specific act) can evoke (what appears to be, from the human perspective) a change Above. In other words , `Above' there are, so to speak, certain possibilities, various states of potential decrees, reflecting the different possibilities of various states of man (both on the individual level as well as on the general, communal level). Man's particular condition of the moment, the status of his present reality, determines the applicable possibility to become realized or actualized. Any change or mutation, therefore, is not in G-d the Emanatory, but in man the recipient.
To rephrase this more subtly:
The petition of Yehi Ratzon is for the emergence of the pure grace and compassion of G-d. To be sure, the Heavenly relationship with the worlds must follow the rulings of the Torah, according to which there is no suffering without initial sin.
Our own conduct is the cause of any agony.
In prayer, however, we beseech G-d to transcend the demands of strict justice (to act lifnim mishurat hadin - beyond the limitations of the law), and to bestow gratuitous kindness. We pray for the Divine grace which is beyond that which is vested and expressed in Torah (the right to which is forfeited by sin), but emanates from the infinitely higher level of the very source of the Supernal grace and love - where Divine compassion is simple and pure (gratuitous, and not reciprocal).
