Maimonides, Guide of the Perplexed (Trans. Pines), 3:27
The Law as a whole aims at two things: the welfare of the soul and the welfare of the body. As for the welfare of the soul, it consists in the multitude's acquiring correct opinions corresponding to their respective capacity… As for the welfare of the body, it comes about by the improvement of their ways of living one with another... in the acquisition by every human individual of moral qualities that are useful for life in society so that the affairs of the city may be ordered. Know that as between these two aims, one is indubitably greater in nobility, namely, the welfare of the soul- I mean the procuring of correct opinions - while the second aim - I mean the welfare of the body - is prior in nature and time.
1. The Ideal and the Real
Mesillot bi-Levavam, 30
The system of Torah and commandments is two-fold. On the one hand, it conveys concepts, instils eternal values, and directs people to the service of God at the highest levels and to the formation of a society worthy to be the bearer of God's presence. On the other hand, it encompasses legislation and commands to combat the forces of evil and destruction that erupt within the individual's soul and the nation's spirit and to ensure that the necessary conditions for spiritual development are satisfied to the greatest possible extent, given each generation's situation and the social, economic, and cultural circumstances prevalent at any given time and place.
Mesillot bi-Levavam, 39-44
… from Creation itself the Torah teaches us that all men are truly equal… These distinctions of status lack substance and are not grounded in reality, for the Creator regards them all as equal. Only one whose imagination is depraved will disregard the fact that all mankind share in Adam's mold; and only the wicked will rule that the status of a slave is sub-human...
Given the dictates of circumstance, the Torah did not require that the principle be applied in full from the outset. Rather, it taught society to advance step by step, until the goal could be fully achieved...
The abolition of slavery is simply a partial realization of the exalted ideal taught by the Torah; and the history of the West makes it clear beyond all doubt that one of the decisive factors in that process was the widespread knowledge of the Torah.
Rav Avraham Yitzchak HaKohen Kook, Iggerot HaRa’aya, 89
...You should know that slavery, as with all the moral, upstanding ways of God “in which the righteous walk and the evil stumble,” (Hosea 14:10) never in itself caused any fault or error… In fact, legal slavery is within the jurisdiction of Torah, and is legislated in order to control certain flaws...
… As a result, the people for whom it is proper to be a slave are, according to the proper functioning of the world (tikkuno shel olam), those for whom expansion of their liberty would bring evil upon them and evil upon the world as they are by nature inclined to a contemptible life. Only through an external burden may they gain integrity and be uplifted… and in order for the integrity that mankind must achieve to be manifest, through the influence of the Torah, it is forbidden, or at least not proper, to abolish the law of slavery, but rather to it should be made to function properly.
2. Halakhic Empiricism
Mesillot bi-Levavam, 156-158
There are tangible results to fulfilling the Torah, and thus through both short-term and long-term observation and tracking the impact and influence of the mitzvot upon the individual and society one can learn about ta’amei ha-mitzvot… “the giving of the mitzvot is not a ‘vain matter’ without a useful end… one should seek in all the Laws an end that is useful in reality (Guide 3:26)”... Maimonides here emphasizes that this ‘useful end’ must be one that can be recognized in this world and revealed to all.
Mesillot bi-Levavam, 176-177
With the ‘choosing’ of the Jewish People and the giving of the Torah to them began an extended process of education in order to realize man’s mission. The history of the Jewish people from the moment it became a nation is testimony to the power of the Torah to mold the character of a people which has been designated to serve as an example for all humankind… It cannot be seen as a hereditary trait, but rather a result of the influence of the Torah.
Rav Avraham Yitzchak HaKohen Kook, Olot HaRa’aya, Yigdal
“God gave His people a Torah of truth – by means of His prophet, the most trusted of His household.” The highest truth is the divine truth, which is granted by the Master of all Creation according to the true order of all reality, according to its highest meaning. Only the consecrated vessel (keli muchshar) of a holy nation, for whom the divine light is embedded in the unique nature of its soul (segulat nishmato), may receive this hidden gift...
3. Free Choice
Mesillot bi-Levavam, 6, 22
The Image of God (Tzelem Elokim) is man's unique quality that elevates him above all other creatures. It is the capacity of free will… And only in the exercise of that free choice does man actualize his essence. A person who… cannot exercise free choice, whether because of external factors that confine him or because of stunted development of his physical and spiritual powers – is one whose soul is dimmed and in whom the Image of God does not appear.
Only if one chooses the good because it is good, and not because of any constraints or pressure, does his choice express his true essence… Obedience to the commandments has value only if it flows from man's free choice. Otherwise, it is nothing more than a purely mechanical act.
Rav Avraham Yitzchak HaKohen Kook, Iggerot HaRa’aya, 555
There are two principal matters which together build the holiness of Israel and its divine consecration. One is the segulah (unique chosen nature) and one is bechirah (free choice), which is dependent upon good acts and learning Torah. The portion of the segulah is beyond measure greater and more holy than the portion of bechirah, yet it is certain that the internal segulah can only be revealed to the extent that the bechirah assists in revealing it… The Holy One blessed be He, who acts with kindness in each generation, arranged the order of souls which need to appear in the world… at times the power of the segulah is greater and the power of bechirah disappears… as the Messianic era approaches the power of the segulah is at its height.
Mesillot bi-Levavam, 8-10
Just as an individual's training proceeds step-by-step until he attains his full spiritual stature, the history of Israel as a whole comprises periods that correspond to the various stages of human maturation. In each of them, the Torah serves as guide and regulator, for the Torah was given not to one generation alone but to all generations. The Torah thus encompasses guidance for each stage of development along the way as well as instruction on how God is to be served by the perfected man and the generation that has attained full wisdom…
The Torah that was given to them guides and molds Israel's image and makes Israel fit to attain the desired goal – making use of Tzelem Elokim in order to resemble Him in all His ways.