And indeed, typically, whenever you see a smiling baby or toddler, we see a face that is overflowing with light and happiness. That's why all people are so attracted to children of this age; they see something pure and wonderful that they have lost and unbeknownst to them yearn for.
We know what happens to that light and faith. It gets buried by the experiences of our life\ and the mind's reaction to those events. Whether it's trauma or a negative reaction to repeated negative experiences, our mind absorbs this negativity and perversely makes it our self-image.
The qualities we are born with are seeds that need to be nourished. Unfortunately instead of being fed, our mind takes control with its negativity and our Buddha nature gets buried, is suffocated, under the detritus of our lives.
Even before we started walking the path, we had evidence that the light was still within us when we would have an internal discussion between the "good" us and the "bad" us. Or when we would see a cartoon showing an angel sitting on one shoulder whispering in one ear and the devil sitting on the other shoulder whispering negative thoughts in the other ear.
We really never thought about it, but where did you think those "good" thoughts came from? They came from your heart, your true Buddha nature. It was alive in us and we didn't even realize it or draw any strength from it. When we would have these internal discussions, the "bad" side would always win because it was more powerful, more forceful.
Even as people walk the path, they are often still in the control of their mind and so they have scant contact with their heart, their Buddha nature, outside of when they are sitting on the cushion.
But it is never too late. Our light is waiting there to be rediscovered and nourished. It take s a lot of courage to disavow your mind and reconnect instead with your heart. All you're ever known about yourself is your mind. You identify with it.
You may be well aware of all the suffering it causes, but because the other path is into the unknown, you don't have the courage to say "no" to your mind and instead turn your will and your life over to the care of your Buddha nature, to surrender your ego to its care.
It comes back to the question I raised in an early post, "Do you really want to be at peace and happy?" If you do, the path is clear, the choice is clear. Have the courage to disavow your mind and embrace the Buddha nature inside you. Take refuge in it.