This is so true. If we only knew how little we know. I don't think our brains are equipped to understand but just so much, to avoid overload. I think this is why we feel and connect with the universal power in a spiritual way rather than an intellectual one.
My sense of spirituality comes come concrete knowledge about the world around me. I think witchcraft begins with a good intuition of the world around us, and involves a trial and error process. In many ways, I view it like I view science. I do believe there are plenty of currently misunderstood forces within the universe which witchcraft taps into that science has yet to tap. However, I do feel even witchcraft has a higher, more concrete understanding to it. I also think a lot of it has to do with personal will. I do not believe the forces which drive witchcraft are celestial, ethereal, or intangible, but are merely regarded as such due to lack of understanding, much as birth, disease, and death once were.