The self is a perpetually recreated neurobiological state.

Imagine, for example, birds. When they look out at the world, they have a sense that they are alive. If they are in pain, they can do something about it. If they have hunger or thirst, they can satisfy that. It's this basic feeling that there is life ticking away inside of you.

We can be more or less conscious when you create grades of focus on a subject that is flowing in our stream of consciousness.

So, you can define emotions very simply as the process of perceiving what is going on in the organs when you are in the throws of an emotion, and that is achieved by a collection of structures, some of which are in the brain stem, and some of which are in the cerebral cortex, namely the insular cortex, which I like to mention not because I think it's the most important, it's not.

When you deal with something like compassion for physical pain, which we know is very, very old in evolution - we can find evidence for it in nonhuman species - the brain processes it at a faster speed. Compassion for mental pain took many seconds longer.

There are ways in which you can make that distinction objective to a certain degree. For example, by looking at responses that could be generated in the brain to exactly the same stimulus and there could be differences there.

Feeling of an emotion is a process that is distinct from having the emotion in the first place. So it helps to understand what is an emotion, what is a feeling, we need to understand what is an emotion.