Mind is meant to think but not to be kept empty; can you please elaborate on this?

When required, think. If thinking happens without your awareness, it is compulsive and hence mechanical. Mechanical thinking is no thinking. To energise your thinking, keep your mind calm and empty. It is a known fact that many scientists think deeply on a subject, go to sleep and in the middle of the night often find answers mysteriously. Learn the art of being empty and in this emptiness when you start thinking, your thinking will have the power and vitality.
In the house of a famous swordsman named Shoken, there lived a large rat that was fomenting trouble. The swordsman brought in a cat to kill the rat. The cat went into the room and saw the rat. Surprisingly, the rat attacked the cat and shamefully the cat had to leave the house. Puzzled by this turn of events, the cats called for a conference to discuss the matter. Amongst them, a wise old female cat volunteered to catch the rat.
The swordsman was surprised to see the old cat. The old cat approached the rat, took it in her mouth, and quietly left the room. The other cats asked the old cat to divulge the secret of her success. The old cat replied, "All of you have used techniques to catch the rat and the rat had better techniques to counter you. I went with emptiness. When one has no form and desire, then one is not a threat to another. Then a great energy …. the divine energy flows through us. When there is 'I,' there is a form and one's form is a threat to the other form. When there is no 'I,' there is no threat to the other, and hence no enmity. I allowed existence to decide who to catch whom? That was the secret of my success."
The great swordsman bowed down to the old female cat and said, 'You are speaking Zen. I have the theory and you have the practise.'
Our ego — the 'I' is like dust in the eyes. When there is dust in the eyes, the whole universe appears to be chaos. Ego is the dust in the eyes of consciousness. Be empty, surrender your ego and allow divine intelligence to flow.