(condensed from Ein Ayah, Shabbat 2:25)


Gemara: One makes the blessing [on Chanuka candles]: "… Hashem … Who commanded us to light …" Where did He command us? Rav Avya said: [It is derived from] "Do not stray from the matter that [the Rabbis] will say to you to the right or the left" (Devarim 17:11). Rav Nechemia said: "Ask your father and he will tell you, your elders and they will say to you" (ibid. 32:7).

Ein Ayah: All the mitzvot are designed for the lofty divinely ordained goal which includes all the good coming to the nation in the future. The path through which the glorious future comes is found in the mitzvot of the Torah, which we received in detail from Hashem, Master of actions, Who foresees the future generations.
Mitzvot of Rabbinic origin certainly follow the path that is paved for the mitzvot in general. However, it is impossible for even the greatest human mind to reach the connection to the wonderful future goals that can be accomplished by divine mitzvot. Therefore, we have to contemplate the source that justifies Rabbinic mitzvot [being compared, through their berachot, to Torah laws].
In order to move on to the glorious future, the nation has to reachshleimut (completeness) in both the material and the spiritual realms. Therefore, Rabbinic mitzvot are drawn from the "well of fresh water" of the Assembly of Israel, which is the foundation of the Oral Law. This gives deep perspective to the, albeit human, intellect, and when Ruach Hakodesh (Divine Spirit) is included, it is possible to gaze onto the future and create appropriate Rabbinic laws.
There are two elements to strengthening the nation. One is strengthening it spiritually and physically in the present. The second is to connect the character of the nation to its critical sources, which ensures that the nation will maintain its purity. If the nation strays from its base connection to its Divine source, its present status will not be able to protect it because then it is not the same nation that is to be preserved. The nation even runs the risk of being destroyed or fully dispersed.
In relation to the goal of preserving the nation in the shorter term, according to the needs of the generation and/or subsequent generations that the Rabbis identified, they instituted Rabbinic laws. This is represented in the pasuk "Do not stray from the matter that [the Rabbis] will say," which applies to the Rabbinical courts of all eras, as long as they are central courts that impact on the whole nation.
In regard to the second element that the Rabbis have to accomplish with their laws and institutions, connecting the source of the nation to its past, the pasuk that represents this is "Ask your father and he will tell you, your elders and they will say to you." Always be connected to your past, because it is great and godly, and it is the source of your success. "When the divine gave place for the nations and separated people into groups, He fixed the boundaries of the nations according to number of the Sons of Israel. For His Nation is His part; Yaakov is the area of His portion" (Devarim 32:8-9). When one looks away from the past, it is no longer possible to find a connection to the nation even in the present. Then the nation turns into a herd of individuals in which each one lacks spiritual connections to others.
Therefore, the Rabbis’ mitzvot are based on a foundation that preserves the Jewish Nation in the present and strengthens and sanctifies it for the future based on its connections to the past. This is done with the ideas of not straying from the Rabbinic leaders and asking the elders for guidance.