Chazal tell us (Brachos 55a) that Betzalel, who was charged with building the Mishkan, possessed the knowledge of how to connect the letters that were used in creating heaven and earth. This knowledge is the quality of da'as. Rav Wolbe writes (Alei Shur vol. I pg. 138) that da'as is a quality which enables one to unite even things that seem to be opposites. With this da'as, Betzalel succeeded in building the Mishkan; a structure that united spiritualistic Heaven with the materialistic Earth.
It might very well be that properly exercising this trait is the very purpose of creation. Hashem presents us with seemingly contradictory entities and our avodah is to fuse them into one single entity. We are given a body and a soul, heavens and earth; and with the middah of da'as we are supposed to unite them in order to accomplish our avodas Hashem.
Likewise, the Gemara tells us (ibid. 33a see Maharsha) that da'as is the ability to strike a balance between chessed and din, and similarly, the Beis Hamikdosh struck a balance between Heaven and Earth. Therefore, one who possesses the quality of da'as is so great that it is considered as if the Beis Hamikdosh was built in his days. Once again we see that da'as is the ability to fuse two opposites into a harmonious expression of avodas Hashem.
This being the case, a vital aspect of avodas Hashem is ensuring that our physical actions are united, i.e. act in consonance, with our spiritual knowledge. There have been brilliant thinkers who preached ethics and morals, but whose actions belied all that they espoused. This is not the Torah way. Any discrepancy between what one practices and what he preaches is duplicitous. It is an expression of shleimus when one's actions mirror their knowledge.
When we hear a drasha, learn a halacha or study a mussar sefer, the knowledge gained isn't meant to be stored away in the recesses of the mind. Rather, as the Ramban writes in his famous letter to his son, "When you finish studying from a sefer, contemplate whether there is an aspect of your learning that you can fulfill."