How can we be sure of what the heart knows?

We can easily define the rules of the material world. We know what a cup is and what a vase is, what is cheap and what is expensive, what is harmful to us and what is beneficial. But when these same things need to be defined in the emotional world, we tend to simply wave our hands and conclude that abstract things are indefinable. In doing so, however, we place ourselves in a position where we are unable to define precisely the most important things in our lives – the things our hearts know.

...