Hi, I am doing my PhD in Informatics and especially graph theory. I came across eigen-analysis numerous times in the context of spectral graph theory. The question: I would like to see an *elegant geometric explanation* of the eigenvalues and eigenvectors of a Matrix A (symmetric, real, >= 0). (Suppose that the only thing I know about linear algebra is how to change between bases and do a few matrix operations) Of course I have looked many textbooks, but they only write math, not essence. thanks!