greater bond energy, more stable? I am very confused about bond energy. In my book, it says "the most stable bond is the bond with the highest bond energy". However, later on it mentions that " A system with low energy is a stable system. Thus, a bond is formed when electron energy level is the lowest". 
So, does high energy means more stability or less stability?
Look at it in this way. Consider the energy to break a bond to be arbitrarily assumed to be at $\pu{0 J/mol}$. Now, there are two bonds, $\ce{A-B}$ and $\ce{C-D}$. Let's say they have energies of $\pu{-242 kJ/mol}$ and $\pu{-378 kJ/mol}$. Clearly, the $\ce{C-D}$ bond has the lower energy.

Now, you can say that a stronger bond needs more energy to break it. So, this means that you need to supply $\pu{242 kJ/mol}$ of energy to break $\ce{A-B}$ and $\pu{378 kJ/mol}$ of energy to break $\ce{C-D}$. You can definitely see that $\ce{C-D}$ needs more energy to break it, and to bring the energy to $\pu{ 0 J/mol}$.

Hope this answer helps you.