Everything in this physical world has its cause and these causes will lead to conditions. Mental phenomena are the product of thoughts. There must be the presence of sense objects, contacts, touches, impulses and emotions to stimulate them.
According to the Buddha’s teaching, Dhamma will arise only when the cause has stopped. When there is no more stimulus of any kind in our heart, these causes are eliminated. At that moment the mind is empty, calm and tranquil. Dhamma will appear.