How can we use the physical world to bring us closer to Hashem? By realizing that everything is from Him, as He is the Source of All. Every morsel of food, every drink, every action, even every breath... is from Hashem. When we use the nefesh for mitzvot, we are becoming aware and connecting to the Source. We blend the nefesh and nishama and bring them together, so they can join as one, at their highest spiritual level and for their ultimate Heavenly purpose.