Why is Matza (vs. Chametz) so important? The word Matza means fighting, and the main fighting is Milchemes HaYetzer. (Chovos Halvavos). Notice how on Erev Pesach people punch and potchke with the dough so it shouldn’t rise and become Chametz which symbolizes the Yetzer Hara. This is why when we left Mitzrayim we were called: צִבְּאוֹתְְׁׁה' soldiers of Hashem, meaning the main role of a person is to be a soldier in the war against his Yetzer Hara.
The Chovos Halvavos describes the Yetzer Hara as the greatest enemy, mixed into your very being, always awake, always plotting, and only by being vigilant and fighting can you be saved. The main battle is not with outside enemies, but with the Yetzer Hara within.
Even the garments of the Cohen Gadol, such as the Choshen Mishpat, symbolize the need to fight for justice and to stand up for the honor of Klal Yisrael. The Torah and Avodah are both essential, but the power of Torah is even greater, as it is the main weapon in this inner war.
