It is as optimistic and promising as it is ambiguous and daunting. "...You shall be holy for I, your G-d, am holy". In one phrase in the middle of Toras Kohanim, the Torah seemingly captures that which we may believe to be the definitive achievement of religious life. Yet, if we were to expect some formula for spirituality or guidelines for disconnecting from the temporal and material, or at least a description of human holiness, what follows is quite frustrating; we next read about revering our parents, observing Shabbos, abstaining from pagan worship, attending to the details of animal sacrifice, leaving some minor gifts for the poor during the harvest and refraining from perjury, theft and withholding employee's wages.
The Ramban explains that the challenge of holiness in this context is a stand-alone requirement to live an elegant life refined by a commitment to the deeper purpose of a disciplined lifestyle and purged, through the regiment of mitzvah observance, of any vulgar or boorish behavior. Having said that, we are still at a loss to understand how Hashem chose the list of observances and mitzvos that seemingly are presented as supporting this graceful and cultured lifestyle.
It is in this context that I find an insight of Rav Alpert zt"l, one of the foremost students of Rav Moshe Feinstien zt"l and a very gifted and creative rosh yeshiva at Y.U., quite intriguing. He suggests that the holiness that is sought in this parsha is not the result of mitzvah observance per se but the attitude and aspiration that we bring to the mitzvah. In this instance the Torah is asking us to creatively find holiness in the way that we observe the mitzvos. Rav Alpert suggests that living life attempting to seize opportunities to do mitzvos while also maintaining a distance from that which is prohibited but tempting is, in short, a holy life.
Guided by Rav Alpert's insight, we can find in the presentation of mitzvos that are listed following the aforementioned passuk different attitudes that we can incorporate into our mitzvah observance which will indeed create holiness.
As a first example of this guidance, we are told to respect our parents and observe Shabbos. According to Chazal the repetition of these mitzvos that were already included in the aseres hadibros and their juxtaposition teaches us that Shabbos observance trumps parental reverence because Shabbos expresses our fealty to Hashem which is incumbent on our parents as well. No doubt that a Shabbos observed through her details, both in the restraint of any improper behavior as well as the heartfelt davening and zemiros, will bring great nachas to Hashem. However, a greater Shabbos observance that also includes discipline, joy, and an acute mindfulness of Hashem will shape a holy life.
Tzedaka is another example. Of course giving tzedaka generously and sensitively are cardinal precepts of the nobility of a Torah life. Yet the holiness that we aspire to achieve enters our lives when the back breaking harvest of every grape also considers which ones will remain for those not fortunate enough to harvest this year.
Rav Alpert here seems to be bringing to life an idea that Harav Eliyahu Dessler proposed and defended vigorously and valiantly. Rav Dessler describes that the moments of nisayon, the struggles and triumphs that shape our religious life and achievements, continue to evolve throughout one's life. When young, the nisayon of Shabbos may be to refrain from texting or to properly enjoy the long summer Shabbos afternoon. Yet as one gets older the allure of texting fades away almost entirely, and the quiet of a long summer Shabbos is much appreciated. It is then that the nisayon of Shabbos, i.e. the opportunity to grow through Shabbos, has shifted to not just avoiding violations of Shabbos, but also consistently living and absorbing the holiness of Shabbos, the "kedoshim tihiyu" of Shabbos.