In this week's parsha, Ki Savo, Moshe says to the Jewish people, "Hashem didn't give you a heart to understand... Until this day."
Usually we connect the brain with understanding and the heart to emotions. However, here it says "a heart to understand". What is the connection between the heart and understanding that we speak of here?
The answer could be found by looking at the Hebrew word used here, Daas (daat/דעת), which we translate as understanding.
Just because someone it smart, doesn't stop him from doing immature or stupid things. Watch a smart child play in the mud wearing his nicest clothes or a genius implode over a trivial matter.
This is because he lacks Daas.
What is daas? Daas is the ability to take your smarts and apply it to your emotional make up. It is the bridge between the mind and heart. This takes time and effort.
For the Jewish people in the desert it took forty years to develop this level of understanding, where their heart and mind beat to the same Jewish drum.
This process can be accomplish by every one of us, through time and effort. Every day we become more in sync, every Torah lesson we apply to ourselves, we become more in tune with Hashem.
The same is true for our relationships. First you get to know each other. But with time and effort the relationship gets deeper and you begin to sense your others way of seeing things. Until there comes a time that you are so in sync, that you don't have to think about it, you just know.
This is "a heart to understand". When your emotions, and subsequently your actions, are in sync with your mind, specifically with your Torah knowledge.