Death becomes obvious fairly soon, I think, but certainly not always right away. I was right beside my aunt when she died, and I could certainly not tell the moment she died, and really saw very little, besides, of course, her not breathing, to immediately say 'she is dead.

I think perhaps we are more aware of breath, which is with us continually while we live, than we realise. Breath moves everything; it stirs the hairs on human skin, and the fur on an animal, animates the body, and when it is stopped, that subtle motion ends. Besides that, the flow of blood, another constant motion, stops, and that too is a process I think we notice when it is stopped.