By saying a bracha with the proper intention, you cause the Shechinah to come to rest on the food you are about to eat.  But more than that, you become Hashem’s partner in the work of Creation.  Why is this so?

The food you eat was created for the sole purpose of providing you the energy to do mitzvos and praise Hashem, and the food reaches the destiny for which it was created.  You thereby become a partner in Hashem’s Creation.

This explains why the text of the brachos is formulated in the present tense, for we say “Who brings forth bread from the earth…Who creates the fruit of the vine…” rather than, “Who brought forth bread…Who created the fruits…”  By reciting a meaningful bracha with kavanah, the purpose of Hashem’s Creation is made complete. ~ Kedushas Levi