...Then we come across one sentence which I believe is the most important in the whole of The Hidden Words. He says, "Rejoice with the joy of your own heart."
It is something that we have utterly forgotten. The western world has forgotten this for centuries. The art of meditation, the art of contemplation, the art of dreaming within oneself, and Bahá’u’lláh wants us to start doing this again. First, it means that there is nothing in the world to make you happy, outside of your own heart. If you possess the whole world, the treasures of the world, the pleasures of the world, they may be momentary pleasures, but they will be bitter sadness throughout your life. They will never bring you any happiness. People are wrong to change the places of their entertainment and enjoyments from New York to Paris, to Rome, to Africa, to Australia. They are searching for it, while they are carrying it along within themselves. He says, "Go deep into thy heart." There is a realm in your heart. There it will spring up with the water of joy, a constant stream of joy will be flowing from your own heart. Nothing will stop it and nothing will be able to give it except yourselves. This is done by spiritual exercise.