Why should one put his trust in H'shem and nothing else? Simple! The source of everything that happens is Him, the tools He chooses to use are powerless. When you want something you go to the source, the lower down on the totem pole the less influence the object has.
pg 465
Nefesh Hachaim
Eliyahu Hanavi teaches us in Mesechet Gittin that every word of Torah man utters on earth is simultaneously being said by GD. "The Torah of Your mouth is better for me than thousands of gold and silver" (tehillim119/72). All parts of the Torah are equally holly to H'shem as every word studied in this world emanates from H'shem's mouth. We can now understand why even one letter missing in the Torah scroll would render it posul.
Gate Four, Chapter 6 pg 143/144