Before I go any further, I do understand the ways that mechanical engineering textbooks explain why stress is a tensor. But all of those explanations seem infused with geometry (which I do NOT mean in a negative way at all); and are demonsrtrations. I am searching for a more concise/abstract reason why stress is a tensor. However, my education in math had been deficient. So am teaching myself new things. And now that I understand a bit more about what a tensor is, after going through many of these wonderful videos: (and many others) ... I am hoping someone can explain to me, concisely, without drawing tetrahera or any of those ways, why is stress a tensor. In other words, beginning with a understanding of what a tensor is, why is stress one of these things? And by that: do not DEMONSTRATE it is by doing a transformatoin..... EXPLAIN why is IS a tensor.