Just getting started

Sometimes, I wonder what exactly makes a person alive. It's not your heart that makes you alive, for when you look at the heart individually at itself, it is unable to beat, thus it is not alive. I've once read that what makes you alive is an idea. An idea of you. It doesn't seem that way to me. Because, I'll then wonder what makes that idea alive. Is it because of a person's thoughts, or simply his character? I guess it is much more complex than that, there is something, really unknown to us that makes us alive. Take for example, would you rather talk to a dead man or an alive man? It is obvious that the choice is that of an alive man, for realistic and practical reasons. It is because the living man is able to respond, to comment, to listen, but a dead man cannot. In the same way, communicating with an idea does not make us alive, nor does it make us dead, it merely makes us a noun, an indication to others that we exists. An idea does not comment or listen, but it does respond. So what exactly makes us alive?