This perspective about circumcision as it relates to an agricultural setting is so interesting. It helped me understand what was meant by perplexing verses elsewhere referring to such things as uncircumcised lips and hearts.
And when ye shall come into the land, and shall have planted all manner of trees for food, then ye shall count the fruit thereof as uncircumcised: three years shall it be as uncircumcised unto you: it shall not be eaten of. Leviticus 19:23
Indeed, biblical language describing circumcision is the same used to describe the practice of pruning fruit trees to increase their future yield: “When you enter the land and plant any tree for food, you shall regard its fruit as its foreskin. Three years it shall be uncircumcised for you, not to be eaten…only in the fifth year may you use its fruit—that its yield to you may be increased.”
Thus, God’s covenant with Abraham—to “make you exceedingly fertile” and to make your descendants “as numerous as the stars of heaven and the sands on the seashore”—is symbolically enacted each time a Jewish male child is circumcised.
…One possible reason that the eighth day was designated for circumcision is that the number eight, representing one more day that the period of Creation, symbolizes eternity or infinity.
According to the midrash, circumcision also symbolizes human partnership with God, an example of our role in completing the divine work of creation. By extension, the word “uncircumcised” often refers in the Bible to body organs that are spiritually incomplete or obstructed: uncircumcised lips, hearts, and ears.
(Frankel, Ellen, and Betsy Platkin Teutsch. 1992. The Encyclopedia of Jewish Symbols.