This essay is from Daniel C. Matt and can be found in his book 'The Essential Kabbalah' published by Harper Colins.

You can mend the cosmos by anything you do- even eating. Do not imagine that G-d wants you to eat for the mere pleasure of filling your belly. No, the purpose is mending.

Sparks of holiness intermingle with everything in the world, even inanimate objects. By saying a blessing before you enjoy something, your soul partakes spiritually. This is food for the soul. As the torah states:" One does not live on bread alone, but rather on all that issues from the mouth of G-d." Not just the physical, but the spiritual- the holy sparks, springing from the mouth of G-d. Like the soul itself, breathed into us by G-d.

So when you are about to eat bread, say the motsi: "Blessed are you, YHVH our G-d, soveriegn of the world who brings forth bread from the earth." Then by eating, you bring forth sparks that cleave to your soul.